Main3s Posted October 4, 2010 Report Share Posted October 4, 2010 I'm having a reoccurring issue with my GTP. I keep getting a bad 02 trouble code along with a "System too lean (bank 1)". It causes the car to... lag (for lack of a better word), almost like a misfire or if you were to shift too early and end up in too high of a gear. But I don't get a misfire code. I've also noticed that it's pulling timing under partial throttle. I'll get 2-5* of knock just under light acceleration. There are a few mods on the car but I'm not running any extra boost. I've changed the 02 sensor (twice) and cleaned the MAF. I checked for vac leaks (just sprayed break cleaner around the intake and the vac lines) and even tried Sea-foam to clean it out. But its still acts up. Any suggestions on which direction I should head next? It seems to be happening more often now. TIA! Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted October 4, 2010 Report Share Posted October 4, 2010 sounds like you could have a wiring issue or do you ahve any exhaust mods??/ Could be causeing it to read bad and then the engine tries to fix the faulse reading?? Quote Link to comment Share on other sites More sharing options...
Benner Posted October 4, 2010 Report Share Posted October 4, 2010 I'm thinkin clogged cat. also check the vacuum/boost lines for any cracks or breaks. Seen that throw some weird codes and give weird symptoms. Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 4, 2010 Author Report Share Posted October 4, 2010 sounds like you could have a wiring issue or do you ahve any exhaust mods??/ Could be causeing it to read bad and then the engine tries to fix the faulse reading?? I sure hope it's not a fucking wiring issue I just replaced the entire wiring harness about a year and a half ago. I have an SLP cat back that's been on the car for about 3 years with no issues. I think my next step may be just to replace the MAF. Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted October 4, 2010 Report Share Posted October 4, 2010 I'm thinking clogged cat. also check the vacuum/boost lines for any cracks or breaks. Seen that throw some weird codes and give weird symptoms. That was my thought but he did not mention having a low cat efficiency code at all just a o2.. and it sounds like he replaced the o2 before the cat not after correct?? Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted October 4, 2010 Report Share Posted October 4, 2010 I sure hope it's not a fucking wiring issue I just replaced the entire wiring harness about a year and a half ago. I have an SLP cat back that's been on the car for about 3 years with no issues. I think my next step may be just to replace the MAF. the maf does go bad on these motors but when it goes bad it will run rough as all hell and it wont sift unless you rev it up and let off... then also it will tend to shift a lot back and forth between all forward gears. and tends to cause the car to stall out very often... ask me how I know... Took me twenty minutes to drive four miles to the store to get the new maf for mine... I got halfway and almost walked home to get my bike and ride there lol I would say swap it with a known good maf first before you go spend 100 bucks or more on one Quote Link to comment Share on other sites More sharing options...
Benner Posted October 4, 2010 Report Share Posted October 4, 2010 Not sure bout the O2 but I've seen cats clogg and never throw a cvode several times Quote Link to comment Share on other sites More sharing options...
Buck531 Posted October 4, 2010 Report Share Posted October 4, 2010 When my MAF died at Dragway 42 last year it didn't throw a code or anything. I was scanning it and the maf Hertz would read 9000 and then the next cell would read 0, then a few cells later read 0 again. Also scan the car. See if the fuel trims are really out of sort. (-16.4 or +16.4). I had a vac on my Lumina way back when and I'm pretty sure it was a vac leak. Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 4, 2010 Author Report Share Posted October 4, 2010 When my MAF died at Dragway 42 last year it didn't throw a code or anything. I was scanning it and the maf Hertz would read 9000 and then the next cell would read 0, then a few cells later read 0 again. Also scan the car. See if the fuel trims are really out of sort. (-16.4 or +16.4). I had a vac on my Lumina way back when and I'm pretty sure it was a vac leak. Yep, the trims are all over the place most of the time they're at +16 (lean if I'm not mistaken) I'll check the MAF hertz too, what should they be at? Thanks for the help. :thumbup: Quote Link to comment Share on other sites More sharing options...
Buck531 Posted October 4, 2010 Report Share Posted October 4, 2010 Yep, the trims are all over the place most of the time they're at +16 (lean if I'm not mistaken) I'll check the MAF hertz too, what should they be at? Thanks for the help. :thumbup: If I remember right idle should be around 2400-2500. From the sound of if you probably have a vac leak. When scanning the hertz, just make sure it doesn't look normal then all of the sudden read zero. Log the scan and open it up in excel because the scanner might not pick it up when just looking at the scanner (cycles too fast). That's how I found my issue. Hook up a vac gauge if you have one too. Should be at least 18-20 inches. Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 4, 2010 Author Report Share Posted October 4, 2010 Okay, so I scanned the car (couldn't record the scan because I just took it to shop and used the TechII they had). Anyway right before it gets sluggish around 45mph, I get multiple misfires in cylinders 1,3 and 5. But once you get on the throttle the misfire goes away The problem seems to go away under full throttle or at least it gets a LOT better. WFT? I'm going to check the coils and plugs to see if there may be an issue there. Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 4, 2010 Author Report Share Posted October 4, 2010 Oh and the misfire isn't there long enough to set a check engine light. Quote Link to comment Share on other sites More sharing options...
Buck531 Posted October 5, 2010 Report Share Posted October 5, 2010 coil packs, ICM, wires, injectors. Have fun Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 6, 2010 Author Report Share Posted October 6, 2010 Well I started small and replaced the plugs and wires last night but the miss-fire is still there. I think my next approach will be to check the injectors. That could explain the lean condition AND the miss. Quote Link to comment Share on other sites More sharing options...
Buck531 Posted October 6, 2010 Report Share Posted October 6, 2010 vac leak? Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 6, 2010 Author Report Share Posted October 6, 2010 vac leak? Kind of though that too, but why would a vac leak cause a miss-fire only at certain speeds or RPM's? I'm going to double check them this weekend just in case... I feel like Dr House working on this damn thing. It's a mystery. I'll run more tests then some more, only to find out that it's some off the wall bull shit. If it wasn't my car this may actually be fun Thanks again. Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 12, 2010 Author Report Share Posted October 12, 2010 So I checked the Vac lines and couldn't find a leak. I also changed the plugs and wires. so I think I've ruled out any vac or spark issues. So my question now is... Is there a good way to clean the injectors? And I'm not talking about a fuel treatment but maybe something to soak the injectors in or flush them with through the fuel rails? Quote Link to comment Share on other sites More sharing options...
craig71188 Posted October 12, 2010 Report Share Posted October 12, 2010 Best way to clean injectors is an AZNU machine. This will do an ultrasonic cleaning and allow you to rack them up and compare flow. Linder Tech in Indy uses these - I don't know of anyone in Columbus with one. Before condemming the injectors, get an injector pulse tool, install an accurate fuel pressure gauge on the rail, pressurize the rail and pulse the injector. Check pressure drop. Repressurize the rail and repeat. All injectors should be within 10% of one another. Generally about a 10-12 PSI drop is normal for stock injectors. Quote Link to comment Share on other sites More sharing options...
Buck531 Posted October 12, 2010 Report Share Posted October 12, 2010 Before doing that, did you check the ICM and/or coil packs? I have an extra ICM here in the garage and a few Coil packs you can try. Does the misfire happen on just one or two cyliners? If it's hitting on 1 and 4 cylinders, then it's the one coil pack. If it's random it might be one or more packs.. or the ICM. let me know. I'm pretty free from noon to 5 pm m-f. What's the PCM tune? Intense? Might want to try to throw a stock PCm in there and see what happens. Quote Link to comment Share on other sites More sharing options...
Das Borgen Posted October 12, 2010 Report Share Posted October 12, 2010 tried a different computer yet? if an o2, vac leak check and MAF aren t the cause, the computer starts to look like a likely suspect but as craig noted, checking injectors is a good idea Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 13, 2010 Author Report Share Posted October 13, 2010 It's only missing in cylinders 1,3 and 5. The front bank which are all on separate coil packs. I mean I guess they could be bad, but there are no misses on in cylinders 2,4 and 6. The tune is a costume tune from Dyno Brian. I'll pull the injectors and have them cleaned and tested and just go from there. I've already replaced the PCM in this car once, so hopefully that's not the issue. Keep the suggestions coming! Quote Link to comment Share on other sites More sharing options...
99FLHRCI Posted October 13, 2010 Report Share Posted October 13, 2010 What about the fuel rail? does it go from the back to to the front? if so a pinched or clogged line would restrict the fuel to the rear bank and leaning out the front bank? Quote Link to comment Share on other sites More sharing options...
Main3s Posted October 13, 2010 Author Report Share Posted October 13, 2010 What about the fuel rail? does it go from the back to to the front? if so a pinched or clogged line would restrict the fuel to the rear bank and leaning out the front bank? Depending on how the injectors read I have a new set of fuel rails I can throw on. Quote Link to comment Share on other sites More sharing options...
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