Resolved 1G Misfire/stutter (stutter feels like spark blow out)

[And_44]

So thought I'd repost this because the old one was getting long and confusing. This problem started off as a slight stutter while cruising and then evolved into a stutter at cruise and misfire/nofire on acceleration and would die when left to idle. I say stutter but it feels like a spark blow out.

When it started the car ran great cold. When problem arouse I could let it sit for 15-30min and it ran good after sitting up until it had been running at operating temp for 15-20min and would start all over.

Now after going through all these checks and swaps. I've noticed that the problem is temp related because the last few days I've ran car and it's been pretty cool and dry and problem was just a stutter at cruise and no misfire, today it was almost 70 and pretty humid and the issue started right at start up while car was still warming up and the car had been sitting for nearly 13 hours.

When I got in car to drive to work this afternoon I was getting a stutter or misfire on what seemed like 1 cylinder felt like spark blow out. I hop on freeway for my 5mile drive at 60-70mph whole time car stutters but it is random and happens every few seconds. As I'm getting off the off ramp and put it in neutral the engine revs down and my RPM's drop to 500 and my CEL comes on. My rpm's stabalize at 700 and CEL goes away but the 1mile drive to my work car is misfiring/no firing and dying when ever I let it go to idle rpm. It died a few times because I had to stop at stop lights and would start right back up but would be doing it's misfire/no fire. I pull into parking lot frustrated and roll into the nearest parking spot because car died as I was entering lot.

I pop the hood and grab my multimeter to check the TPS which checked out in spec. I then check the resistance of the 1-4 and 2-3 on my coil with my ohms meter set at 20k I was getting .013 on both coils didn't do the other 2 checks on coil as curious if car would idle to check o2 sensor. So I then go to turn on car and cranks and goes to idle with the sputter at idle and was kinda bouncy I was curious if it would die if I unplugged the TPS so pulled it and it died right away... Plugged it back in and started car again it ran without sputter this time and I realized that I needed to get into work or I'd be late so closed it up.

When it start's misfire/no fire it gets worse at or near 0psi and gets worse up to 5psi if it can make it past 5psi it smooths out just a VERY little. It's almost stock I've ran with a hacked maf since I've had car for almost 6months this problem started almost 5 weeks ago. Has a full 3" turbo back exhaust, and the turbo is a 16g. Stock boost and everything else. Running 10-11psi. Got a aftermarket boost gauge, use the stock BCS that has had the restrictor removed. When it's misfiring/no fire the boost gauge holds steady.

Things I've changed for new are injector seals, wires and plugs (NGK 6's copper), things I've swapped with known good parts MAF, and coil. Things I've tested cool ignition module, ICS, TPS, both coils. Things I've checked while hot O2 sensor, TPS/ICS. The TPS/ICS tested fine and numbers were in check. The O2 sensor however was steady at .4-.5 and when the throttle cable was used it would jump just slightly to .7-1.1 then fall back down to .4-.5. I pulled the ECU and checked that out as well and it looks great, the caps have been replaced and no burn or runs in it.

I'm getting pretty frustrated on what this can be. I don't want to start spending the money on parts right and left to just have the same issues. I don't mind testing just a waste of money to replace good parts. I do have the time though for testing.

I'll be doing a Boost leak check tomorrow. As of today it seemed like it was behaving like a intercooler pipe blew off. I am getting fuel and spark. And when running on a stutter/misfire/nofire I can smell the unburnt fuel. And during the cool weather I know that the air is denser and warmer air is thinner so I have no idea at the time.

Any suggestions will be greatly accepted and tested.

 

[muleunit]

Yeah definately do a boost leak test and update us tomorrow, that should have been one the first things you did.

 

[And_44]

"sigh" Well I'll update ya'll in a bit. I did the boost leak test and results weren't good;( I couldn't get it past 12psi. And when I removed the air source it quickly dropped to 5psi and slowly fell from there. Heard a few area's that were leaking and biggest seemed to be coming from the oil return line from the turbo. It actually was dripping oil from the line.

Built a nice boost leak tester from Home depot But only have access to air at gas station. Gonna be borrowing a air compressor and do it at home were it's quieter.

Did find out that the previous owner did upgrade the turbo to a s16g;D (49178-05200) But I'll be busy for a few days repairing these leaks.

"EDIT"

I'm looking to purchase new intercooler pipes for the beast was looking at EBAY. I can't afford to upgrade to a FMIC but these pipes appear that when I do upgrade to a FMIC I could possibly still use them.

But right now do these appear as if they'll fit the stock side mount hook up? http://cgi.ebay.com/ebaymotors/UNIVE...item5d29e0e920 http://cgi.ebay.com/ebaymotors/Turbo...item1e5cca6fb0

 

[DSM1G90]

almost sounds like the ECU is acting up on you somehow ... something is getting ready to go. Not too crazy on those ISC readings that you posted for they seem a bit low, but as long as it working for you, we'll leave that alone and peek into elsewhere for your probs.

Good luck - DSM

 

[And_44]

Well, an up date. I've recently done a boost leak test and it wasn't good, going to be fixing the leaks over the next 2 weeks and when get paid going to replace the ignition module. I've noticed that when the misfire's start and I feel the module it's extremely hot to the touch compared to other parts near it. I'm thinking that it's faulty under heat. When it cools (usually 10-20min after turn off) the car will start and run fine until it heats up again. Starting to think it's diffently the module. It's easy to test but by the time I get it ready to test while it's hot it is cool and operating again. So will be replacing it when I get paid next and if it doesn't solve the issue I'll just return new part;D

 

[And_44]

Update 7/15

I did a boost leak test yesterday with free air, was able to get the boost up to 15lbs before my tester blew apart. But when at 13-15psi the boost wouldn't hold but would gradually very slowly creep down. My lower inter cooler hose clamp was loose. I left my PCV hose attached to VC/Intake so was loosing the pressure that way through dip stick. Sooo I got a bad PCV as well. Gonna be getting a new one from dealership instead of Autocrap.

Now that I know the intake is leak free have located an almost 100% intact 1990 that the owner is parting out. So will be picking up just about anything and everything I need for cheap. Ignition Module/Coil, ECU, throttle body (with ICS/TPS), and a few other misc. parts.

I'll keep ya'll updated. When I pick up the parts I'll be replacing one at a time till it stops mucking up.

 

[And_44]

Okay, another update. I replaced the module and coil with another the the studder when cold is gone, but the misfire still happens. I'll be replacing the throttle body with new FIAV, TPS, ICS this after noon and see if that helps at all. If not I'll swap the CAS and ECU after.

I got lucky and found a 1990 parts car and was the 2nd guy to get his hands on parting it out. Got a coil, module, whole throttle body with sensors, CAS, ECU, front turn signal light (mine was discoloured). Parts car was out of comission because the t-belt broke and ran fine before. All the parts appeared to be in good condition.

 

[And_44]

Turned out to be a faulty Alternator.

 

[pearl4gtsi]

just a quick question. how did you know it was the alternator? im having a similar problem. read your post and thought to try disconnecting the wires on the alt and see if it goes away. did that but it didnt go away. probably not the same as your problem but it hit a note cause i just replaced my alternator.

 

[DSM1G90]

..and by disconnecting the wires while the ALT is running, it raises hell with the regulator and can blow it out in a real quick.

Try not to do that again...

 

[And_44]

My misfire seemed weird it wasn't misfiring on 1 cylinder but seemed like it was a 2 cycle firing for example 1 and 2. And 3 and 4 where the misfire. When the engine revs increased it would improve slightly.

When I went to adjust my timing, I hooked up my light to my #1 spark plug wire and wasn't receiving a signal so I thought I'd try #4 and got one there. So I switched my wires at the coil and had a signal now on 1 and not on 4. I was little curious as to why so when I looked at the coil the leads on the back were directly behind the post that was getting the signal. I don't know much about electricity but know that electricity follows the shortest path to ground and that only a certain amount of electricity could be discharged from one post then moves to next. I tested this by putting my light on the 2 and 3 wires and had same issue.

I eliminated the coil and module by swapping them out, and all my modules and coils tested within spec even the coil testes fine hot, it burnt me some but did it when hot.

I then was thinking there wasn't enough juice flowing through the wire to tell the light to flash. That's when I was searching for some kind of voltage regulator for the ignition system and read that it was internal in the Alternator.

When learned that. I remembered back to when all this started. Shortly before it got bad I replaced my crappy Pacesetter tubular exhaust manifold with a 2g one. And when I went to torque it down realized that my o-ring on the water pipe running from lower radiator hose to water pump behind exhaust manifold decided to fail and it leaked ALOT of coolant onto my Alternator. That's when I also learned that coolant isn't good for Alternators.

I feel pretty stupid now but a few months later I pulled the alternator and saw it was the original 20year mitsu alternator and when I put new one in the misfire was gone.

Now though it's just being a normal dsm and out of commission 2-5 days a month in hunting down random annoying stuff. My latest being an idle problem which I believe I've found to be leaking capacitors on ecu.

 

[fourgsixthree33]

I read through this entire thing. You give great detail. I am having a similar problem. My car will sputter/missfire at lower RPM's and only while driving. When in neutral or park, the car sounds great when you rev it up. But when your driving in gear, it will sputter. Then you give it alot of gas, and it smoothes out. This problem isnt all the time. It happens at different times.

Wednesday, I am getting some new plugs and wires since I need them anyway. I hope to god that is my problem. Otherwise, it's a never ending egg hunt.

I didn't realize a poor alternator would give you these kind of problems. You would think you would have starting issues or a dead battery. Anyway, I enjoyed reading your post.

 

[And_44]

LoL, np. Yes, My battery was new so it was in good condition. And the problem got worse over a period of time. So the strain on battery was only great toward the end.

And I know the feeling about the egg hunt. My beast is 21 years old. I love it and know it's a black hole for money and repairs but I enjoy it and it saves me butt loads of cash doing the work myself. Gives me lots of good explanations to fiancee about why I have to buy all these tools and gadgets and experience;D

But if it's running it's alot easier, funner, and cheaper to buy the diagnostic tools and test all you can before replacing parts. Also if you can find a parts car or someone parting out one try to pick up used parts and keep a closet of them so when a problem crops up you can swap parts. Used parts are a heck alot cheaper when I say cheap I mean ChEaP. Again there getting old so new parts are retarded expensive. But come with lifetime warrenties.

Love hearing from ya'll, and Good luck to ya'll;D

 

[Vapezilla]

Did the problem include spiking tach? I have the same issue also just when the car is in operating temp