NEED HELP WITH P1074 error. CAR KEEPS FALLING ON ITS FACE

Guys, need some help here. Have a 2003 cobra vert that has given me a couple of problems that we can’t seem to figure out so looking for some guidance. The first issue is that I cannot get the car to finish the system ready procedure so that I can complete an emissions test. In the two years I have owned it, I just stays in system not ready mode. Will list the mods below but the car has stock manifolds a bassani catted x-pipe, EGR etc.


Secondly, since the day I bought the car, there are times when you are getting into the boost that the car will just fall flat on its face for a second or two and then pick back up again.


Recently in order to help with eth system not ready error I replaced the EGR valve thinking that maybe it was stuck. After replacing the EGR I found the car to be drive remarkably better, more power, smother etc. then during one of the times I was getting on the car, it cut out again. That caused a check engine light with the code P0174 – System Too Lean (Bank 2). I had never gotten this error before.

Mods

1st gen 2.3L Whipple with 3.0” pulley
60# injectors
JLT High Boost CAI
SCT 3000 MAF
Single blade accufab TB (I believe)
New NGK plugs
Chiller Killer
Black 306 modified FPDM with power wire upgrade
Dual Deutchworks 340lph fuel pumps
PPRV delete

Not sure if I am forgetting something.

My mechanic (who isn’t an expert with mustangs or cobras) has been fiddling with it and trying to datalog and believes it’s a fuel related issue. He’s had the tank down flow tested everything and on that end everything looks fine. He initially thought it was an MAF issue so had me replace the MAF. I replaced with a SCT 2600 as I don’t have any aspirations about making more power. Now he is fixated on the MAP sensor as he is convinced that it is being pegged being only a 2 bar and the car currently running 17#.

I did have the car dyno tuned last year but the tuner thought the car was missing at high RPM and shut the car down. He checked plugs etc and also thought it was fuel related. At the time i was running stock pumps and BAP which i then replaced with the upgraded pumps, upgraded FPDM, PPRV delete and a new fuel filter.

I have never heard of this issue before and tried searching on the sight but can’t find much info. I originally thought it may be an injector, but he doesn’t think so as we would be getting a different error code.

Any help, guidance assistance would be appreciated.

I didn’t build the car. Bought it as is and have been trying to work out the gremlins ever since. Car has ~82k miles.

Last thing, I am getting the dreaded battery light flicker from time to time, comes on for a minute or two and then comes off.

When you installed the BA2600 MAF did you have the car retuned for it? As for the drive cycle code chances are the tuner turned off the rear O2’s in the tune. If they’re turned off the cycle will never complete. The MAP sensor shouldn’t be an issue. Lots of people running over 17psi with no issues. First thing is to fix the alternator. Whether it’s a bad connection or the alternator going out. There needs to be a steady supply of voltage for everything to work correctly. To be honest I wouldn’t be surprised if that’s the issue. If the voltage is low the pumps can’t keep up. After that I would start datalogging. See if you can replicate the issue and catch on a log. If you can you’ll probably be able to figure things out quick.

No, I have not had the car re-tuned yet as I am still dealing with the same issue. I specifically told the tuner to make sure everything is switched on. He said it is. If the rears were switched off, wouldn't I get a CEL? Yes, I know I need to deal with the alternator, i believe however that this problem was occurring even prior to the battery light coming on. I have asked my mechanic to at the very least take a look at the connection as the previous owner said he changed the alternator right before I bought the car (like the day before) and I don't think i have put more than 2k miles on the car since buying it 2 years ago

If you weren't running a 2600 MAF before then you need a new tune. You can't just swap MAFs unless its the same model. Turning the rear O2's off keeps the CEL from popping. Have you scanned it to see what monitors haven't completed?

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Would the voltage tables need adjustment as well since you swapped pumps?

I totally agree about needing to retune given the MAF and the pumps but trying to avoid that at this point until we know we have fixed the bigger issue.

No, he hasn't scnned yet to see what has registered and what hasn't. Been on him about that but wants to figure out the cut out issue first

If you're not going to tune it then you need to go back to the old MAF. Having a MAF without a tune is only adding to the problem. Who is your tuner? They should be able to tell you what the issue pretty quick if they're having you datalog like they should be. It honestly sounds like a tune issue to me. Probably something in the fuel pump tables. I don't mean to be a dick and I don't know if you're buddies with your mechanic, but if he won't take the two minutes to scan for monitors I'd find someone else. The two problems could be related.

BLOWN9646 said:

Would the voltage tables need adjustment as well since you swapped pumps?

Click to expand...

Ideally yes. But the ECU does learn the voltages needed. The tables are there for when the ECU has been reset.

Thanks for the advice. Will put the old MAF back on the car. In the process of replacing the Alternator and will be back at it.

Alright, so new alternator is in, solving the voltage issue but that didn't change the cutting out at WOT. Still in the process of data logging to see what is happening. Did a search on the forum and there seems to be quite a few posts of people having similar issues with the car cutting out at WOT but not many follow-up responses. In some cases they have blamed tuning. Not sure if this should be my next step, taking back to the tuner......

I hope you swapped back to the original maf it was tuned for, if not theres no point in trying to help.

Not sure, I didn't ask. Will confirm

By changing mafs the ecm now has no idea how much air is going into the motor. This effects afr and load. So your car could be super rich or lean and if load is thrown off timing will be thrown off. Its a great way to toast your motor and cause driveability problems.

Thanks. Just confirmed the original MAF is going back in the car today and if the weather holds up (we had torential rain over the last day or two) should get some data logging to see what's happening.

Will revert when I have some additonal info

btw.....what would you gap plugs at? The car has a whipple Gen 1 2.3 pushing 17lbs. I believe I am at 0.3 or 0.32 but have read that people are going much tighter when boost is over 15lbs?

.28

that's what i thought. Thanks again

Does anyone have sct tuner software that can read a data log and give me their thoughts

Actually it’s in excel so if anyone wants to take a look and give me some advice would really appreciate it

post it up

Ok so update. Brought the car to my tuner and he couldn’t figure it out. Whatever he did, thwbcar would start to pull fuel and go lean as boost increased. Regardless of how much fuel he would add, once in boost, the car cuts fuel pressure.

The only clue we got was that we accidentally took the vacuum line off the fuel pressure sensor and with that off, the car would hold consistent fuel pressure but he couldn’t tune it with the vacuum off.

We are thinking that it’s possibly a bad fuel pressure sensor, messed up vacuum lines or possibly a bad FPDM. I replaced the stock FPDM with a Black 306 modifies FPDM so maybe that is the issue. Unfortunately didn’t have the stock FPDM with me so couldn’t swap it out