2009 cobalt ss. K&n, catless dp, zzp tune. I have had all mods done for 15k miles or so with no issue.

I got the p0087 code, and random misfires. Went to reduced power mode. Only does this at around 4200rpm and/or 17psi. Backfires machine gun style, pops, misfires and won't tach any higher.

In attempts to fix this issue, I have done the following;

I have replaced HPFP. (Roller on original HPFP looked perfect, no marks at all) Replaced coils and plugs gapped at .029. I have checked for boost leaks. I have replaced injector seals. And checked fuel pressure at the test valve before the HPFP and get around 80psi under load. I have also checked the wiring from the plug on the HPFP. None of this helped at all. Same exact issue.

I am at a loss. The only thing I could guess is possibly the part that the fuel pressure test valve is on. I'm not sure what it's called but it's part number 12636128. I have checked fuel pressure with HP tuners and it all seemed to be around 2500psi.

Please help me and point me in the right direction! Thanks in advance.

 

Any chance it could be the fuel pressure sensor on the end of the fuel rail?

 

Make sure to check the wiring that goes to the fuel pump as shown in this thread.
p0087 & p0089 codes/ power reduced - Cobalt SS Network

Also, I had a similar issue awhile back and it was the giant wire loom that runs to the right of the intake manifold. It was rubbing against the high pressure fuel pump. It was rubbing and causing engine power reduced.

I have a picture of it.
https://www.cobaltss.net/g/picture/5128664

 

I had already checked out all of that. But I finally found the problem. The first o2 sensor was bad. It was telling the car it was all the way lean, so the car was trying to dump 30% more fuel. Replaced it and it runs like a champ. It only took a month of searching and replacing parts. A few emails back and forth to zzp, and some data logging, but I got it all figured out. Thank you for your reply!

 

02 sensor appears to be a maintenance item on these cars.

Probably no more than 100k miles on the stock one.

 

since your running an LNF can i ask why your plugs are gapped at .029?? if your running stock plugs they should be .032-.035

 

Hawkssoccer11

I was having an issue with blowing out the spark at the factory gap. I'm pushing 30psi of boost. Couldn't keep it from misfiring. Haven't had a problem since I gapped them tighter. It was suggested by zzp, and it worked!

 

30 psi on a ZZP tune?

 

Yeah, not just an off the shelf tune. The tune has been adjusted a handful of times, with quite a bit of data logging.

I guess I should have said "tuned by zzp" not "a zzp tune"

 

I assume we aren't discussing a stock turbo car.

 

Only mods are upgraded sensors, k&n, stage 4 clutch, catless dp, and lots of data logging and tuning. Stock turbo on 93 octane. I've been on this tune for 20k miles and the only problem has been spark blowout, and this o2 sensor issue. Max boost is set for 31psi actually. But with the temperature and environment I live in, I have only seen 27-29 on the gauge. I've never seen it actually make 30-31. With all the tuning I have had done, and data logging, everything is set pretty tight. It's just my travel car, and doesn't get beat too bad.

 

well you are running way too much boost

Are you sure your tune isn't running out of fuel and throwing the code.

Most tuners don't go over 24 psi.

 

You need to setup a math function in hptuners to look at the difference between desire fuel pressure and actual fuel pressure, the 0087 code sets for low fuel pressure compared to desired (1500kpa/218psi difference) and it's not just at WOT that can set the code. It should be pretty easy to quickly see the spot if you have both commanded and actual fuel pressure plotting on the same graph section. Log your driving and some WOT pulls, since zzp is tuning you I would get in contact with them about this issue because it can be tuning related.

 

If his fuel trims were +30, it could have been running out of fuel due to this. If its running fine after the new O2, id say its fixed.

 

Missed that post.

 

Yeah that's how I figured out the issue, I logged a bunch of data and sent it to zzp. They reviewed it all and the o2 sensor was telling the car it was all the way lean, when everything else said otherwise. So the car was trying to dump 30% more fuel. I changed the o2 sensor, and it's back to normal! I knew it had to be something other than a tuning issue, since I have had this same setup for 20k miles and never had an issue. Thanks for the input guys! I really appreciate it!!

 

I'm pretty sure I had a similar issue..I had p0087 and p0089 and popped the hood and wiggled those wires around and it seems to be fine ever since that so it definitely does happen I'm glad I came across your post 🤘🤘🤘