MSP setup has major stumble

[xelderx]

Quick list of the parts on the car

MSP Turbo w/ ATP 6lbs Actuator
Thunder manifold
SLS J/mid-pipe no cats
Custom FMIC with HKS SSQV
MAF relocated to boosted side
Head ported
MSP Injectors
MSP stock sparkplugs
MSP ECU
Vacuum holds a steady 20 at idle


Codes the ECU is throwing right now

P0140 O2 Sensor CKT No Activity Bank 1 Sensor 2

P0090 Fuel Pressure Reg 1 Control Circuit

I've been driving the car around for about a day to try and work out a major stumble in the powerband. As soon as the car sees about 4lbs of boost it starts to stumble really bad. It acts like it is dumping way too much fuel. Anything more than 1/4 throttle and it stumbles until the boost drops back below 4 lbs. I'm hoping a new O2 sensor and making sure I rewire the extension jumper correctly will solve the stumbling problem. I unplugged the 2nd O2 sensor completely and it did not change the way the car ran. I'm also very curious about the P0090 code. I've only seen it posted once on this entire forum and that post never received an answer. I don't have my factory service manual with me at the moment. Hopefully the diagnostic procedure for that code isn't too complicated. Between those two codes I'm hoping I can solve this stumbling problem.

I've seen some people suggest going with the Bosch universal 4 wire O2 sensor. That might be the first thing I stop and get today.

 

[orphman]

first code usualy means an o2 sensor.. thats all i know.. hope it helps

 

[xelderx]

Yea. I'm going to sort that one out first as it is the most obvious.

 

[SIBalla23]

The code for the 02 sensor looks like you wired it up poorly. That should be a quick fix. Let me check the workshop manual about the other code, and will try to help with that.

 

[BradC]

Agree with everyone else so far, check the o2 sensor wiring. If the wiring is cool, replace the sensor.

What's the deal with the FPR circuit though?

 

[SIBalla23]

I checked the workshop manual I have. Its the protege5.ugly.net one and I can't find the code. But I got an idea, you said you installed injectors. That means you removed your fuel rail. Your fuel pressure regulator is connected to that. Check to make sure your vac line is secure on it, check your electrical connections and gas lines.

 

[mryellermp5]

Do u have the small purge valve installed

 

[xelderx]

Do u have the small purge valve installed

I'm not sure what you are referring to there? Do you mean the purge solenoid valve?

 

[xelderx]

Ok...I worked on the car for about 6 hours today. I rewired the 2nd O2 sensor and it seems to be working properly. That is one thing we can eliminate as the stumbling problem is still there.

I reset the ECU and went for another drive the P0900 code returned as well as P0303 (Cylinder #3 misfire). I talked with Kooldino and he suggested I bypass the FPR Solenoid. That didn't affect the way the car ran so we moved on to replacing the FPR Solenoid and the actual regulator itself. Luckily I had spares of both. When I was really pushing the car it would hesitate so badly that it was like a rev limiter and the car would not accelerate any farther. The ECU was going into limp mode unless I backed off. I checked the codes again and it was still showing the P0090 and P0303.

I reset the ECU again and drove home. The P0090 code has not returned, but it may be because I am not forcing the car to stumble as much now. It's very hard to keep it from stumbling though as the car can build boost so fast. It stumbled a little more on the way home so I had the code checked again. This time it is a P0300 Random Cylinder Misfire. This could be the main problem. I'm going to pull the spark plugs and coils tomorrow to check them.

Does anyone think it's worth it to have the MSP ECU reflashed? It was hooked up to a MPI tuner before I got it so I have no idea if it learned any bad habits.

 

[ND4MSP]

I guess you could for s****. I don't think it would solve any problems though. With those mods could you possibly be hitting spark/fuel cut(whatever) and the codes not evan be related.

 

[xelderx]

I guess you could for s****. I don't think it would solve any problems though. With those mods could you possibly be hitting spark/fuel cut(whatever) and the codes not evan be related.

That is exactly what it was. I regapped the spark plugs to .028" amd she runs just fine now. The P0090 code was probably a result of the terrible misfires. All is well. Thanks to everyone for helping me out with it.

 

[ND4MSP]

That crazy to think a few hundredths of an inch in a plug gap could make a car run so rough. What was it at before? Hows the car pull at 6psi with those mods?

 

[ho bag]

I think you might want to consider the 1.8l coils at this point. If your blowing out spark that easy it might be time.

 

[xelderx]

That crazy to think a few hundredths of an inch in a plug gap could make a car run so rough. What was it at before? Hows the car pull at 6psi with those mods?

I don't know what the plug gap was before. I wasn't paying attention when I put them in. I've been an N/A guy for too long. Gapping them down completely slipped my mind. The car pulls really good, but I know the stock ECU is holding me back a little bit. You can feel the flatspot where it gets really rich. It actually sounds a lot faster than it really is. The turbo spool and BOV are really, really loud.

 

[xelderx]

I think you might want to consider the 1.8l coils at this point. If your blowing out spark that easy it might be time.

I've got a set waiting to go in the car. I've got a 626 Valve cover to go with them, but I've got to do a little trimming on it before I put it all in.