misfire code, and engine stutter

[mustg5]

I have done a 1g into a 2g swap....and i have heard that when doing the CAS swap, you will get a misfire code......well i have gotten it, and i cleared it.....well i was driving and all the sundden the engine studdered and the check engine light came on, so i checked it, and sure enough it was the misfire code. I thought that it only threw a code, and didnt do anything engine wise....well i cleared the code, and about 10 miles later, engine studdered again and light came on again.....midfire........what u think is going on??

 

[markgolf123]

I had the same problem when i put a 1g in my 2g talon. If you go to www.magnusmotorsports.com they have a 1g in a 2g tech page. Go to the bottom of the page and it talks about the misfires. I did the fix reccomended and it worked.

 

[mustg5]

yea seen that....but i only heard that it will throw a code, not actually misfire

 

[Swat517]

you need like a 10k potentiometer connected to one of the wires on the ecu...if i can find the lin on how to do the mod i will post it..or if anyone else finds it please post it

 

[Dyncaus]

When the computer throws the misfire code, it also puts your car in a sort of safe mode I believe, which is the studdering you are feeling. As for the potentiometer fix, do some creative searching on it and you will find that most people consider it a rather risky fix since it has caused a few engines to blow due to the ecu thinking it is in a higher altitude than it really is. The only real fix to my knowledge is DSMlink. I myself have the TPS unplugged which prevents the computer from searching for misfire codes, but this also makes it hard to tune the car. IF you want a safe bandage, I would recommend unplugging the TPS until you get DSMlink, the potentiometer mod seems too risky IMO.

 

[Hangman]

you need like a 10k potentiometer connected to one of the wires on the ecu...if i can find the lin on how to do the mod i will post it..or if anyone else finds it please post it

I have the same problem with my car and it's a 2g into a 1g. Did the potentiometer and it worked for me. I also have the instructions on how to fix it too. Here it is, hope it works for you. Mine bothered the shit out of me, I was about to crash it and get a new car. Lolz.

IF CHECK ENGINE LIGHTS OCCUR! TRY THIS:

(Blake Heisler's Fix for misfire Check Engine Lights (CELs) when putting a 1G Cam Angle Sensor (CAS) on a 2G)

Many people using the 1G CAS on a 2G head have been running into problems with misfire engine codes while at cruise. Many different things have been blamed for this and many different fixes have been attempted.

This fix will keep the ECU from looking for misfires at all. This is the criterion that must be met before the ECU will start to look for misfires:

1. 300+ seconds of steady state RPM less than 80% throttle position

2. Engine coolant temperature -10C or higher

3. Intake air temperature -10C or higher

4. Barometric pressure greater than 76 kPa

Now if we can get one of these values outside of the criteria the ECU won’t check for misfires. The value that would be the easiest to change would be the barometric pressure sensor. We’re going to add resistance to this value so that the ECU will see less barometric pressure than what there really is. This will also lean the car out so you should see a performance increase as well. Depending on the car and altitude you might need to add more fuel with an AFC.

So let’s get started, Parts needed:

A 10K potentiometer (although a 5K would probably do just fine). These are available at any electronics store, if you go to Radio Shack ask for a volume control knob because they don’t know what a potentiometer is

Wire strippers

Soldering iron

Step 1: Remove the access panel on the driver’s side of the center console. You should now see four plugs with a ton of wires going to them.

Step 2: Pull out the top plug, it’ll be the one that’s the hardest to reach. Locate wire #85. It’s orange with a white stripe.

Step 3: Cut the orange wire in half. Solder one end of the wire to the center peg of your potentiometer. Solder the other end to either the left or right leg, it doesn’t matter which. Turn your potentiometer all the way counter-clockwise.

Step 4: Plug the harness back in and start up the car. It should sound like it did before you did any modifications. If the idle is choppy or the car won’t run you turned your potentiometer the wrong way.

Step 5: Add resistance to the barometric pressure sensor by slowly turning the knob on the potentiometer. Drive the car around; if you get a CEL then add some more resistance. Keep doing this until you no longer get the CELs.

That’s it, special thanks to Marco for pioneering this mod and to all the guys on the DSM1Gina2G Yahoo group for all the discussion, ideas, etc.

 

[Hangman]

Took me 3 mother fukking months of day and night researching for this piece of information. Thanks to Jason(aka Elimint0r from here and xceedspeed.com) I'm back in loving my car again.


EDIT: Spelling.

 

[forcedfedgsx]

this sounds like my prob, got a 1g head and 2g botom. this thing is really pissin me off.

 

[Dyncaus]

Does anyone have a datalogger with the potentiometer mod, I would be interested to see if the timing issues that have caused some peoples engines to blow with this mod are really as bad as they are made out to be. It would seem that tricking the ecu into thinking you are at a higher altitude than you really are would have to cause some problems seeing as how combustion temperatures and pressures would be different at different altitudes.

 

[flipnotize]

i had that same prob a couple months ago. couldnt figure it out for weeks.. then i check i replace my spark plug and wires.. the coil, and took apart the cam sensor.. 2 10mm bolts, wiped it down and re lube it with oil. works fine now......

 

[latvianrkey]

I am thinking about doing this mod, but I keep hearing people saying that it is dangerous. I'm not sure why it would be dangerous because I tune with an EGT gauge and a datalogger. If you're getting knock or higher than normal EGT's you need to add more fuel. I'm not sure how the "car is thinking it is at a higher altitude" has anything todo with the way you tune. Someone please clarify this, because I do not understand how you could "blow your engine."

 

[krummel45]

I am having the same problem but i have dsm link how do i fix the problem, i have dsm link?

thanks

 

[latvianrkey]

uncheck the box for misfire codes.

 

[krummel45]

Great idea, this will not hert any thing will it ? Otherwise why would it become triggered? Also this proble just started recently out of the blue could this be normal or would it be doing it form the beginging ?

 

[latvianrkey]

from what i understand, there isn't actually a misfire taking place when the CEL comes on. The 6-bolt swap confuses the ECU, and it "thinks" there is a misfire. This makes the car go into "limp mode" and it usually sounds like a big BURRRRRRRRRRRP. Uncheck the misfire box and your problems will be gone, there is no misfire actually happening, the ECU just thinks there is.

 

[BISHILVR]

for some reason i'm thinkin that keydiver chips take care of that problem with one of their chips.........????

 

[u6t9]

hey krummel, did you uncheck the misfire box on your dsmlink yet? i want to know if it worked because that's the next mod i want for my car and i want to know if it worked, i cant even drive one mile today without it misfiring.... makes me want to wup up on a mustang or something.... let me know

 

[krummel21]

I jsut got back from vacation ill see if it works and then ill post.

 

[DSM_One]

I think I'm experiencing the same problem of misfire and stutter of a 1g-2g swap with my 90 GST but I have not done the swap. In fact, I have done no modifications to this car except for a K&N air filter. I have replaced the valve cover to fix an oil leak. The spark plugs (NGK BPR7ES) and the wires are new. The valve cover gasket is new (FELLPRO), oil cap and gasket are new, and new OEM Fuel Filter. Also the ECU was replaced with a rebuilt one 3k miles ago to fix an idle surge. I have not checked the coil pack or the CAS because I don't know how to check it

Here is what happens: When the car had time to cool down, like in the morning, I have to pre-heat the car first. When it reached its normal temp, the engine starts to stutter like the long BURRRP described by latvianrkey and CEL lights up. I then have to shut it down and start it again, then its ok for a drive. If I don't do that, it will misfire while cruising.

Is this the same problem? Is the CAS or coil pack going bad? What else should I check?

Thanks in advance.

DSM_One

 

[u6t9]

i would check your coil packs and your transistor unit, also check your timing.
i dont understand why you replaced your ECU to fix an idle surge.... what year ECU did you put back in the car?

 

[latvianrkey]

just an update. I did the potentiometer mod for my 1g in a 2g swap. It got rid of the misfire, but if i crank it too much, i get a CEL for the baro. sensor. (turn it only as much as you need to get rid of the misfire code.) However, I did notice that now my low throttle settings require more fuel to keep the trims at 0. Im tuning the WOT settings now to try and get good timing at 21 psi. on 93 octane. Will keep posting this thread if i do anything that may be related to the Potentiometer mod.

 

[44pirate]

I get it occasionally. I clear it with my pocketlogger and drive on. I've been considering the POT fix. Watching here to see what happens.

 

[DSM_One]

i would check your coil packs and your transistor unit, also check your timing.
i dont understand why you replaced your ECU to fix an idle surge.... what year ECU did you put back in the car?

Thanks. I will check the coil pack and the transistor unit this weekend. I found on my Hayes Manual how to do them but I don't know where the transistor unit exactly is. The drawing is not exactly clear. Is it under the coil pack? I will take a pic of what I suspect it is and post it here for confirmation if nobody minds. As for the timing ... I still have to research on it

As for the idle surge, I did all the cheap fixes even replaced the tb but that didn't work. I checked everything except for the ECU and it turned out later that the ECU was going bad. I bought a rebuilt ECU for a 1990 eclipse (MD128625) and once it was installed, the idle became normal.

 

[krummel45]

unchecking the box works great no problems yet!