[RESOLVED] misfire help P0300 - ISC & coil results

[bboyalan]

Hey guys! I've been trying to fix this w/ my dad since Friday night, but I must resort to asking for help now as it is simply too time consuming w/ college and all...

Long story somewhat shorter [so I can explain the current situation]:
-A'PEXi dp + high flow cat installed friday noontime [nice, powerful drive home]
-installed boost/vac gauge on that friday afternoon [easy source taps]
-tried drilling through passenger footwell w/o looking
-ended up going through steering wheel boot [success!]
-key in ignition = no go for instrument cluster
-car would crank, but not start
-ends up I drilled through the wires behind and beneath the battery...
-reconnected and wrapped up wires
-car cranks, starts, but has terribly low, bogging idle [200RPM near death]
-smells like unburnt gas [not enough air in mixture for combustion?]
-checked plugs and wires
-replaced 1-month old NGK G-power platinums [toasted] w/ *new* NGK iridiums
-did the throttle SAS + BISS adjustment properly to help idle @ 400-500 RPM
-test drove and had POOR acceleration + threw p0300 code for random misfire
-erased code & grounded the brown plug for ignition timing adjustment
-boost and vac leak check
-test drove again w/ the same poor acceleration, P0300 code, but <400RPM now

SO NOW [and I apologize for the brief summary] I'm here w/ some diagnostics/results and hoping to get some good direction and recommendations. We pulled the plugs out after the code was thrown to see if any weren't firing and they all checked out okay. I also tested the ISC [Idle Speed Control] and came up with 41 Ohms on each [supposed to be 28-33]. In addition, I tested both the primary and secondaries of my coil pack. The secondary checks out within proper range, BUT the primaries were showing 11.2 for each [should be 0.70 - 0.86]. My NGK wires are 1-month old and have good resistance in them.

What should I be testing for or replacing next? I have such a terrible headache from thinking about this on the constant and I've devoted practically ALL of my study time towards searching the forum + trying out new things. If there is any other information that's needed, then I'll try my best to provide them. Any help is appreciated!

ps: this thread seems to have a similar problem minus the first half of b.s. I had went through.

 

[bboyalan]

i've never installed a cas, but a cps is quite a job. or at least the way i did one it was. the motor mount has to come off just like you would for a timing belt job. i would definitely make sure its bad before swapping.

Wow, no kidding. I caught a glimpse of this and in the repair manual... seems like a difficult and time consuming task just as you've mentioned.

 

[Artago]

Just a bit of extra info here. I have a brand new OEM CPS. It was installed by a shop when they dropped my motor in. Unless they F-ed up the install I highly doubt it's the CPS (but you can check it out anyways if you'd like). Regarding the CAS... I have the original CAS that came with the car. It has never been replaced. It was on my old motor and was swapped into the my motor. It's possible it was installed incorrectly or calibrated incorrectly. I really don't know.

Does anyone know the procedure for testing the CAS? Can you post a link?

Anyways, just wanted to throw that out there.

Tom

 

[bboyalan]

That's an interesting point Tom. I'm assuming my car still has the original CAS as well [140K miles] so maybe we have a culprit? Unless there's someone who has changed theirs out without a success story. Then again, we each have our slight uniqueness to our own situations.

I was trying to search for how to test the CAS, and ran into just a few posts:

using a multimeter
using your hands and ears
should read 5v on 2 pins

Anybody else want to chime in? Seems like we're getting closer to a good answer together.

 

[PieEyedPiper]

I forgot to mention, when I saw it a quite a few posts up, I'm almost positive there is no adjustment for a 2g CAS. So I'm not sure what your mech was referring to there Tom. But I'm glad your CPS is relatively new. Makes me feel better about not yanking all my timing equip just to find out.

 

[PieEyedPiper]

Thanks for the replies again. The car feels as if the timing is more "retarded" than it should be [no pun intended ]. I wanted to adjust and advance the timing, but soon realized it was only allowed for 90-94 [correct me if I'm wrong]. To answer you questions, the car atm can't really go passed 2k rpm. At THAT point, it feels it's nearing 4.5k+ or so. The CEL comes on only after driving for a few minutes, but never at idle. I've yet to go on the freeway, and don't intend on trying until this is fixed hahaha.

I wanted to get the NGK BPR6ES plugs last week, but I just needed a quick, temporary substitute that I could buy locally even though the Iridiums were $7/ea . I WANT to try testing the CAS and CPS, but this whole conundrum [!] is just so energy and enthusiasm draining. Also, before I forget, the clutch/flywheel are both stock so nothing on that. I've retightened and checked ALL I/C clamps and vacuum lines and VAC always reads at 18-19 in/HG.

How difficult is it to test/replace the CAS and CPS?

Sooo... by tomorrow afternoon you'll have posted results of your BLT and you'll have the right spark plugs?

 

[Artago]

That's an interesting point Tom. I'm assuming my car still has the original CAS as well [140K miles] so maybe we have a culprit? Unless there's someone who has changed theirs out without a success story. Then again, we each have our slight uniqueness to our own situations.

I was trying to search for how to test the CAS, and ran into just a few posts:

using a multimeter
using your hands and ears
should read 5v on 2 pins

Anybody else want to chime in? Seems like we're getting closer to a good answer together.

Wow, wicked threads. Lotsa good info. I read several posts and it looks like the CPS does play a role in ignition. A dead CPS or CPS connection will cause the car not to fire.

So here's what I'm thinking. If a none functioning CPS will cause the ignition not to fire then a dying CPS may cause a car to, intermittently, not fire .

Assuming that's the case then the intermittent firing will throw a P0300 code.

Make sense?

Also, regarding the testing of the CPS, it seems like there is no solid info on how to test it so it may be hard to determine if ours are failing.

So I think just replacing it the CPS might be the easier thing to do. The only catch is that if the CPS is good but the connection is bad then it wont fix the problem.

But I'm tried of this CEL and I'm willing to take the shot to fix it.

So here's what I'm thinking. I'm going to pick up a CAS from Auto Parts Fast at RockAuto ($62.79 + Shipping and install it. I figure the CAS is cheap enough for me to just try it. If it doesn't work then oh well but if it does then we can finally "cure this cancer" that has plagued our DSMs.

I just hope the connection is good. If anyone finds a write up or instructions on how to test the CAS connection then please post it.

In the meantime I'll do a little more research and then I'll order the CAS.

Tom

 

[Artago]

I forgot to mention, when I saw it a quite a few posts up, I'm almost positive there is no adjustment for a 2g CAS. So I'm not sure what your mech was referring to there Tom. But I'm glad your CPS is relatively new. Makes me feel better about not yanking all my timing equip just to find out.

Yeah my CPS is brand new, installed a few months back (less then 2000 miles on it). Regarding my mech, he mentioned (back when he was installing my motor) that he was going to try to adjust the CAS because my car was misfiring and idling rough. I don't think he ended up doing it because I look at the CAS and it doesn't look like you can adjust it either.

But he seemed to say that a bad CAS can cause a car to misfire and he wanted to fix it. So it's making me think that the CAS can cause the P0300.

Tom

 

[Artago]

...and you'll have the right spark plugs?

Yeah NGK BPR6ES for the win

 

[super97gst]

Wow, wicked threads. Lotsa good info. I read several posts and it looks like the CPS does play a role in ignition. A dead CPS or CPS connection will cause the car not to fire.

So here's what I'm thinking. If a none functioning CPS will cause the ignition not to fire then a dying CPS may cause a car to, intermittently, not fire .

Assuming that's the case then the intermittent firing will throw a P0300 code.

Make sense?

Also, regarding the testing of the CPS, it seems like there is no solid info on how to test it so it may be hard to determine if ours are failing.

So I think just replacing it the CPS might be the easier thing to do. The only catch is that if the CPS is good but the connection is bad then it wont fix the problem.

But I'm tried of this CEL and I'm willing to take the shot to fix it.

So here's what I'm thinking. I'm going to pick up a CAS from Auto Parts Fast at RockAuto ($62.79 + Shipping and install it. I figure the CAS is cheap enough for me to just try it. If it doesn't work then oh well but if it does then we can finally "cure this cancer" that has plagued our DSMs.

I just hope the connection is good. If anyone finds a write up or instructions on how to test the CAS connection then please post it.

In the meantime I'll do a little more research and then I'll order the CAS.

Tom

as for the CPS, the ecu uses the cps to determine fuel intector sequence and ignition timing and engine rpm's. the fuel and ingnition systems will not work if the ecu does not recieve a signal from the cps.

the cps can be checked though. using a multimeter check the center pin for power. it should get 12 volts. thats with the key on. the signal output and the ground are the 2 other pins in the terminal. check the signal output by plugging the connector back in and probe into the signal output terminal, thats the one on the left side of the connector. just ground the other side of your multimeter to ground somewhere. with the multimeter in the signal output terminal have someone crank over the engine. it should produce .4-4 volts.

then to check the other pin in the connector, which is ground, turn your multimeter to ohms and measure the resistance between the ground terminal and ground, like anything that is ground on the engine. it should be less than 2 ohms. if all of that checks out then its good. if not, then you get to swap it out.

the mitsubishi shop manual also says something about unplugging the plug wires from the coil before you test the signal output pin in the cps sensor. also the terminals in the cas are the same 3 pins. signal output on the 1st, power supply on the 2nd, and ground in the 3rd. it gets checked the same. hope this helps everyone. im gonna run through all of mine tonight and see if i can figure out whats wrong on mine.

 

[Artago]

as for the CPS, the ecu uses the cps to determine fuel intector sequence and ignition timing and engine rpm's. the fuel and ingnition systems will not work if the ecu does not recieve a signal from the cps.

the cps can be checked though. using a multimeter check the center pin for power. it should get 12 volts. thats with the key on. the signal output and the ground are the 2 other pins in the terminal. check the signal output by plugging the connector back in and probe into the signal output terminal, thats the one on the left side of the connector. just ground the other side of your multimeter to ground somewhere. with the multimeter in the signal output terminal have someone crank over the engine. it should produce .4-4 volts.

then to check the other pin in the connector, which is ground, turn your multimeter to ohms and measure the resistance between the ground terminal and ground, like anything that is ground on the engine. it should be less than 2 ohms. if all of that checks out then its good. if not, then you get to swap it out.

the mitsubishi shop manual also says something about unplugging the plug wires from the coil before you test the signal output pin in the cps sensor. also the terminals in the cas are the same 3 pins. signal output on the 1st, power supply on the 2nd, and ground in the 3rd. it gets checked the same. hope this helps everyone. im gonna run through all of mine tonight and see if i can figure out whats wrong on mine.

Do you know what the test values should be for the CAS test? I'll test my CPS too but like I mentioned earlier I have a brand new CPS so I doubt it's dying. Thanks for the post.

 

[super97gst]

it should be the same as the cps specs. the test for both of them is the same.

as for the PO300 code my gst is throwing. like i said before i cant even drive my car just like bboylan. anyways, i just ran a check on the tps, as pieeyedpiper was saying that was a main cause of these codes. the mitsubishi shop manual says the tps should read 3.5-6.5k ohms on between pins 1 and 4, and pins 2 and 4. mine reads 5.05-5.15 on both of those. so the first tests show the tps to be good. but the last test is back on pins 2 and 4, ill be reading like 5.15 and as soon as i start to roll the throttle open it goes blank. i mean its not reading any ohm reading. i tried it 4 or 5 times to make sure i was on the pins each time and it was always the same. has anyone thats had a tps go bad ran a check and it done this?? the manual says if one of either of the tests is bad then the tps is bad. im thinking this might be the reason my gst wont run right. and the reason for the po300 code, at least in my situation. but i dont want to order a new tps and it end up not being it. like i just did with the coil pack. anyone who has tested their tps let me know what you think. or if someone wants to go test their tps for me and let me know if it does or doesnt do the same thing mine just did. thanks a lot.

 

[bboyalan]

super97gst: Hey! Wow, seems like we're really in the same boat . I was having the SAME, EXACT issue when testing pins 2&4 for the throttle opening. Get a bright light and look closely at the TPS and there should be markings on the unit itself for each pin - should be a circle, +, -/ground, and something else. I realized that I had been testing the wrong pin for that 2nd test so just my thoughts just in case you were pulling the same mistake as me. Post back results!

 

[super97gst]

super97gst: Hey! Wow, seems like we're really in the same boat . I was having the SAME, EXACT issue when testing pins 2&4 for the throttle opening. Get a bright light and look closely at the TPS and there should be markings on the unit itself for each pin - should be a circle, +, -/ground, and something else. I realized that I had been testing the wrong pin for that 2nd test so just my thoughts just in case you were pulling the same mistake as me. Post back results!

well thats no surprise to me really. i have seen shop manuals be wrong before. i tested pins 1 and 4 first, then pins 2 and 4. both with the same result, thinking, like you that i might be testing the wrong pins. well, if 2 and 4 are not the correct pins to test while opening the throttle plate then which ones are??? i tried it on all of them and didnt get a different reading on any of them. honestly, if figures though that it probably won't be something that is actually easy to get to. im sure it'll most likely end up being the CPS. which, im telling you, is a real pain in the ass to swap out. i really need to do a t-belt job anyways, so if it is the cps on mine i'll just do it all at the same time.

i was thinking about this this afternoon and i thought of this. ok, when this problem starts up and the motor goes to shaking real bad because of the idle being so low, the knock sensor has to be detecting major knock just because of the extremely low idle. maybe not, but if it is then the ecu is in turn pulling timing because the knock sensor thinks theres knock. and that would make it run that much worse. that may be way off base, dunno just a thought. i just wanna get something figured out here so i can finally have my car to drive again, this really sucks

 

[bboyalan]

Here's a rough picture of the TPS taken from an above perspective. If you look at this picture closely and at yours, you'll see that there are 4 symbols: -, S, O, and +. The first test was between pins "1 & 4" which correspond to "-" & "+". The second test was between pins "2 & 4" which SHOULD correspond to "-" & "O". Often, people including myself, will mistake the 2nd pin for "S" because it's the 2nd pin if you're looking at it from above. I hope that helps a bit.

Yes, we must fix our cars so that we may enjoy them rather than stare at them sitting in the garage. ATM, I'm becoming more convinced it's either the CAS or quite possibly my ECU [since I DID screw up my electrical at one point].

 

[bboyalan]

I was browsing around my engine bay trying to find the CPS, but I seriously have no idea WTH it looks like or where it is. The repair manual says it's near the water temp housing, but all I could find was this:

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What exactly IS this? It only has 2 pins, so I just assumed that wasn't what I was looking for.

On the bright side, I was able to test my CAS [if we were testing the right damn thing ]. Is THIS a connecting harness from the sensor:

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It appears so because of the bracket it's held by which the manual reflects.
The results are as follows:
+12v when "on" = PASS
GROUND = PASS
4.8-5.2V on sensor wire during idle = FAIL

During idle, the sensor was only sending a fluctuation of 3.2V - 3.4V. Now assuming we tested for the correct sensor, is this enough evidence/testing for me to order a new CAS? If so, I'm going to place my order tomorrow morning. I called around the junkyards today, but nobody had one on them. I'm simply considering RockAuto, Autozone, or Kragen for this one. Any opinions guys?

 

[PieEyedPiper]

You have a '95 so I think yours is on the other side of the valve cover, behind the intake cam gear.
I've actually not seen a CAS from a 2ga in person, sorry I can't be more help.

 

[super97gst]

well, mines a 97 but the sensor youve got circled there is the CAS. and also, i think you should be testing voltage while its being cranked over, not while idling. i guess its a possibility its the ecu, but our cars are doing the EXACT same thing, and i havent drilled into ne electrical stuff. so im thinking its either the cas or the cps. and on the cps you wont be able to see it without taking off the lowest timing belt cover. it sits behind the timing belt on the side of the block right down at teh crank.

when you tested your tps on the 2 correct pins did it test good while you were rolling the throttle plate open??? i'll test my CAS and CPS today and post back and let you know something. i think if one of us can find the guilty culprit then it will most likely fix both of our cars.

 

[bboyalan]

Hey again. Yes, my TPS for the 2nd test showed the same reading as the 1st test [when closed]. As I opened it, the #'s were rolling accordingly to throttle position. Oh, and before I forget, it was a little difficult to catch the cranking #'s since the car starts promptly after one click !

So I was getting sad that I'd have to order the Crankshaft Position [Angle] Sensor online and wait, but MIRACULOUSLY, I managed to find ONE Autozone a few miles away that had ONE in stock It's $61.99 [just an FYI] and I'll be picking it up this morning. My dad and I are just going to take a stab at changing all the stupid belts while trying to change the sensor deep within. I shall post back results whenever we get this tedious job done....

LET'S SOLVE THIS PROBLEM ALREADY!!

 

[super97gst]

Hey again. Yes, my TPS for the 2nd test showed the same reading as the 1st test [when closed]. As I opened it, the #'s were rolling accordingly to throttle position. Oh, and before I forget, it was a little difficult to catch the cranking #'s since the car starts promptly after one click !

So I was getting sad that I'd have to order the Crankshaft Position [Angle] Sensor online and wait, but MIRACULOUSLY, I managed to find ONE Autozone a few miles away that had ONE in stock It's $61.99 [just an FYI] and I'll be picking it up this morning. My dad and I are just going to take a stab at changing all the stupid belts while trying to change the sensor deep within. I shall post back results whenever we get this tedious job done....

LET'S SOLVE THIS PROBLEM ALREADY!!

yea, no kidding

i was checking my tps again like you were talking bout the labeled numbers on the side of the housing for the pins. yea, well, mine doesnt have any. WTF i dont know waht the deal is with that. i know there were some things different on just the 95 models, and i think that might just be one more of them. anyways, no worries. im just gonna wait until you get a new CPS on yours and see if that fixes anything. are you gonna try to start on that in the next couple of days???

BTW, if your gonna go ahead and replace your t-belt and b-belt and all the accessory belts while your in there i offer a word of advice. dont buy your tbelt and bbelt's from an auto parts store. advance or o reilly's acc. belts always seem to b e ok, but the main belts i would be going to the dealership or gettin em online. the only bad thing about that is that you'll have to wait a few days more to get it all done. and if you're like me right now you want it back together as soon as possible. good luck man, i hope that fixes it so i can get an idea of waht to fix on mine. i might go ahead and replace the CAS in the next day or 2, so i'll let you know what happens when i swap it out.

post back when you get the new CPS on there.

 

[bboyalan]

UPDATE:

So while I was out of the house, my dad took the liberty of taking the DS engine mount off and raising the engine a bit to make clearance. It turns out that the harness I circled in my previous post and tested was ACTUALLY the Camshaft Position Sensor. SOOO... THAT one was going wrong according to the test result comparisons. I already have the Crank Angle/Position Sensor with me, but gaining access to the one installed is a PAIN IN THE BUTT. There's so little room down there to take off what's in the way. The Camshaft one is pretty easy. It's directly behind the rear cam gear. We're going to try and replace BOTH Camshaft and Crankshaft sensors with all the accessory belts as well just because everything is pretty much setup to do so. Wish us luck!

 

[Artago]

Wow. I don't check the thread for 24 hours and all this action is going on. With regards to the CAS and CPS, I was going to order a new CAS just to take a shot in the dark but if you (bboyalan) have already ordered a CAS and CPS then I guess I'll hold off until you post back results. I really hope it's not the CPS because I have a brand new one in the car already and it is a pain to swap.

Since the CAS is easy to install, can you leave your old CAS on the car with the new CPS bboyalan? That way we can determine which one is the culprit by not changing both at the same time? If the new CPS makes no difference and then you install the new CAS and the problem is fixed then we'll know for sure.

Thanks all for working so hard on this.

Good Luck,

Tom

 

[super97gst]

Artago, a lots gone on in the last 24 hours because we want this problem fixed ASAP. . and besides, i really dont think its gonna be the CPS on yours if it was just replaced. if the CPS goes down the car is going to be undrivable. just like ours are at teh moment. but maybe yours is the CAS. bboyalan, im gonna go ahead and order both CAS and CPS this afternoon. about the CAS, thats waht i was saying before, that the one you had cirled in your pic was the CAS. i really hope it ends up being that one. the other is as absolute pain to replace.

when i was running the codes a couple weeks ago i forgot to mention that mine also pulled a p1104 code. the diagnostic machine said that was a manufacturer air/fuel metering malfunction. well that sounds like the MAS right? when i looked the code up on the mitchell code program it said it was the turbocharger wastegate solenoid. that doesnt make a lot of sense does it. i dont know that it has anything to do though with this problem, i doubt it does. does any of yours pull that same code?? i think the reason mine pulled that code is because i did away with the BCS when i installed my Greddy profec b boost controller. i'll get a new CAS and CPS ordered this afternoon and as soon as i get em in i'll get them right on. or at least the CAS, depending on how your CPS install goes. good luck man.

 

[bboyalan]

super97gst: Have you unplugged/disconnected your BCS? I'm not talking about the vac and boost lines, but the actual plug.

Just thought I'd post up two pictures for a visual of these sensors' locations.

PS: Removing the lower timing belt cover = PITA x 1000. LUCKILY, I did enough research on here to realize you only need to remove the 4 smaller bolts on the crank pulley to remove it

Here's the CAMSHAFT sensor:

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And here's the CRANK sensor:

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I had to remove one pair of pulleys near the DS headlight to remove a bolt holding in the lower timing belt cover. Anyway, there's the update. I shall post back later. Good luck everyone!

 

[super97gst]

no i havent unplugged the BCS plug. the crank sensor should fairly easy to get to on yours. mine is not in the same location though. mine is on the other end of the cams, on the end of the valve cover. thats why you have to tap a set of aftermarket cams on the 95-96, because of the cam angle sensor. i've done one of those CPS's on a 99 model and it was a major PIA like i said before. good luck man, i hope it works out well. are you gonna swap the CPS then crank it and see if that fixed it or are you gonna do both of them at the same time?? it would definitely help me out if you did one at a time. but i know since its all behind the timing belt on yours it'll be a little harder. i think im gonna just wait till you get those 2 swapped out before i buy them.

 

[Artago]

^^ Thanks for the updates all. I'm eagerly awaiting the results.

Tom.