My car decided to fugger up the a/f ratio

[hpram99]

... at least that's my semi-educated guess.

Haven't had too serious of problems with the car, but after getting off the interstate, driving around 35mph I get some very mild boost, anddddd misses all the way down to idle. The OEM boost guage is reading (incorrectly) as high as it will go. I can only go 5mph, and still get a miss here and there.

Car starts perfectly, idles perfectly at 740-760rpm and seems otherwise fine. the OEM Boost guage reads abnormally high, even when at idle, shows that it is near the point of what used to be positive boost. Drive 40 feet in first gear at <5% throttle, it quickly reaches the top of the guage as if I'm pushing 15psi. Quickly sputters back down from 2000rpm to 300rpm, sputters for a while, then eventually reaches 750 again.

Seems to most definately be an air/fuel problem, I can't remember what the OEM boost guage uses to give it's guess, I know it's a mixture of electrical sensors around the engine...

anything common I should look for first? I just lost my other car and don't exactly have the time for this to be breaking down on me

EDIT: To make your reading easier, here's what I've done.
1. Have done a proper boost leak test.
2. MAS and wiring measure normally on a multimeter, car reacts when unplugged.
3. Completely cleaned out MAS, intake, intercooler, and other plumbing.
4. Spark plugs are new, spark is strong and normal across all 4 wires.
5. OBDII pulls no codes, except the same EVAP code I've had forever (car ran fine with this code).
6. TPS/IPS test normal.

exhaust REEKS of fuel

Car still falls flat on it's face at any hint of throttle.

SOLVED!
Read post 18

ECU was bad.

 

[cobb]

Sounds like a boost leak man... i would look for a blown cuppler or maybe a ripped pipe.

 

[hpram99]

no, there is no boost being created to leak out.

 

[cobb]

OK well then i would check you plugs, plug wires, check see if maybe you MAS is still plugged in. How do you know its not building any boost??

 

[hpram99]

plugs are new, wires are clean, no arc spots.

does your car produce boost at at 1/10th throttle in 1st gear?
trust me, it's very far away from boost.

 

[TurboTJ]

Sounds like a boost leak man... i would look for a blown cuppler or maybe a ripped pipe.

I agree. When I have blown off a pipe before, It kinda does the same thing even though I am not building boost. Check all your pipes and fittings. For that to be the problem, It would probably have to be a pretty big leak(blown of IC pipe).

Does anyone know if the stock boost gauge is driven from MAF or MAP?

 

[hpram99]

I agree. When I have blown off a pipe before, It kinda does the same thing even though I am not building boost. Check all your pipes and fittings. For that to be the problem, It would probably have to be a pretty big leak(blown of IC pipe).

Does anyone know if the stock boost gauge is driven from MAF or MAP?

for the 3rd time, it's not a blown off pipe, It idles perfectly stable, can rev slightly perfectly fine. Was completely dissasembled and checked, rechecked, and reassembled 2 weeks ago.


Stock guage runs off a combination of a few sensors in the engine, the ECU puts it together and spits out a guestimate reading.

 

[PieEyedPiper]

Can you describe the procedure you used to do your boost leak test?

The more you tell use the better we can help you.
I look forward to your response.

 

[hpram99]

Can you describe the procedure you used to do your boost leak test?

The more you tell use the better we can help you.
I look forward to your response.

hehe I bet you do, I'm not a newbie by any means, I'd be doing the same thing

Each part was cleaned out by hand, the intercooler was leak tested with UV dye under 20-25psi. Rubber hoses were molested by hand, and hard plastic was put under much less stressful testing with air caps on both ends and soapy water.

everything electrical has good connectors, and is still plugged in. no chaffed wires. I ended up re-wrapping some of the main harness that goes underneath the battery tray, but none of the individual wires had damaged insulation..

you'll kill me for this one, but I didn't do it.

aftermarket cheap BOV venting into the atmosphere

 

[PieEyedPiper]

Your testing methods, while quite vigilant, are missing one detail that can make or break your car.
You must, after reassembly of your intake tract, leak test it by pressurizing the entire system (or at the SMIC inlet) to 20psi and using soapy water, as you used before, to uncover any leaks. If you can hold 20psi or close to it for a reasonable amount of time (more than 10seconds) it's safe to say that you can eliminate a boost leak as the cause of your problem.

I know we all keep shouting out boost leak test at you, but once we can 100% eliminate that as a factor your problem and the solution will become much more clear to everyone trying to help you.
Let us know!

EDIT: recirc. that bov!

 

[TurboTJ]

for the 3rd time, it's not a blown off pipe, It idles perfectly stable, can rev slightly perfectly fine. Was completely dissasembled and checked, rechecked, and reassembled 2 weeks ago.


Stock guage runs off a combination of a few sensors in the engine, the ECU puts it together and spits out a guestimate reading.

You posted nothing about an actual test. With what we were going on, that is a perfectly logical hypothesis. You don't need boost to have a blown off IC pipe be a problem. We are all just trying to help. You also said and air/fuel problem further pointing to a boost leak.

At this point, I am thinking that the BOV is the problem (aka boost leak). Let us know the results of the test. Here is a link if you don't know how to build a boost leak tester.
http://www.vfaq.com/mods/ICtester.html

 

[ZyklonBZombie]

i would make sure all the bolts on the exhaust manifold are tight ... i had a similar problem a few years back and that was the culprit ...

 

[GVR4592]

Do a real boost leak test, recirculate the bov, and don't ask for people's advice if you're not willing to listen.

 

[hpram99]

Your testing methods, while quite vigilant, are missing one detail that can make or break your car.
You must, after reassembly of your intake tract, leak test it by pressurizing the entire system (or at the SMIC inlet) to 20psi and using soapy water, as you used before, to uncover any leaks. If you can hold 20psi or close to it for a reasonable amount of time (more than 10seconds) it's safe to say that you can eliminate a boost leak as the cause of your problem.

I know we all keep shouting out boost leak test at you, but once we can 100% eliminate that as a factor your problem and the solution will become much more clear to everyone trying to help you.
Let us know!

EDIT: recirc. that bov!

I know, I know. It's been running on an open air BOV since I bought it, haven't quite decided what to do about it since the injen intake plumbing that is on the car doesn't have a hose fitting to recirculate it to!

Did find that the top intercooler clamp was leaking, it's taped up now, no more leaks. Had no effect whatsoever.
I don't know if I was clear enough, but this is not a minor performance issue, the car falls flat on it's face at any hint of throttle, if it were to be a boost leak, an entire clamp would have to blow itself off, and completely open up the loop...

I dissasembled the MAS and found it way too dirty, cleaned it up, still no change.

My DMM is broken, it's measuring 2v with nothing attached thanks harbor freight. I ordered a real DMM from Fluke, waiting for it to arrive so I can test the wiring and MAS readings.

Tomorrow I'll probably do the carb/choke cleaner trick, and spray the manifold, I'm guessing if it's a leak, it has got to be big enough for this to work.

Anything else I'm not thinking of?

 

[flashburn02]

You have a bad cam angle sensor I'd bet. Its easy to check as only two bolts hold the sensor in. Mark it with a sharpy so you can put it back in and be sure you pull it out when the crank is in TDC position. Pull it out and if it crumbles apart in your hand you know why.

you should also refer to you haynes for testing methods of your CAS.

 

[hpram99]

You have a bad cam angle sensor I'd bet. Its easy to check as only two bolts hold the sensor in. Mark it with a sharpy so you can put it back in and be sure you pull it out when the crank is in TDC position. Pull it out and if it crumbles apart in your hand you know why.

you should also refer to you haynes for testing methods of your CAS.

Cam angle sensor is fine, measures normally on my multimeter, didn't crumble, had a little oil drip though.

Not sure why I'd have to pull the cam sensor in TDC??

I don't have a haynes manual I've gotten used to the factory manuals.

 

[hpram99]

TPS/Idle also tests out fine, using both the ECU voltage test and basic Ohm sweep. Wiring tests out fine also.

Anything else? I'm still suspecting the ECU is at fault here, but I don't exactly have a spare to test with.

 

[hpram99]

Finally got it fixed, ECU was bad. Car runs normally now.

now to recirculate that BOV...

 

[91TurboTalonFWD]

I have an ECU Question... would a bad ecu start my car at times and at other times not want it to start?

 

[hpram99]

I have an ECU Question... would a bad ecu start my car at times and at other times not want it to start?

haha no

 

[91TurboTalonFWD]

What could be causing it to start at times and at times not start?

 

[tfoti]

Actually it can cause intermittent start and no start. Happened to me. Check and see if the stock boost gauge reads zero when the key is in the on position. The CEL should also come on. If those two things don't happen the ECU isn't turning on. You should also pull the ECU and see if there are any leaking caps.