jt_2002_ta

iTrader: (3)

well my car started running like **** the other day, it has no power at all and the a/f gauge shows very lean all throughout the rpms. a lot of the time the car has a hard time getting over 4000 rpms driving, but in park or neutral has no problems (seems like its revving slow). it idles good though but you can just hear that it doesnt sound as healthy. it also seems to be very hot although the gauge still reads @210.

here is the codes its showing
p0103
p0102
p0200
P0418

hopefully somebody can point me in the right direction with this, hoping its one problem that maybe is throwing other codes. it had some transmission codes but those are just left over from the th400 swap that still need to be tuned out.

so far ive unplugged the maf filter and drove it around the block and nothing changed,checked injector fuses,checked to see that all injectors where plugged in. any ideas where to start? could a weak fuel pump cause all this? broken valve spring? they got about 7000 miles on them with a ms3.(cause it has trouble under load passing 4000 rpms, thought one may of broke or bound up) there is one common with all these codes a bad pcm. wouldnt there be other issues if the pcm was bad?

hrcslam

Your VE tables are off. Get an SD tune and it'll run a lot better.

I'd check all grounds from block to harness and harness to chassis. Probably a bad ground.

jt_2002_ta

iTrader: (3)

how could they be off? its been tuned by the best tuner in kansas city ad has ran fine until now. i am thinking of going sd though.

hrcslam

You likely had a MAF tune. Most tuners will not get the VE tables perfect if they adjust them at all for a MAF tune. If you disconnect your MAF your car goes into SD mode and reverts to the VE tables for fueling. If it runs like crap with the MAF disconnected then it's likely your VE tables are off.

I learned this the hard way (blew a O2 off during a run) and now have a SD tune and a MAF tune. I tuned for SD incase my MAF or something else fails forcing SD mode. SD tunes take a while to do (up to a few days) to get dialed in just right.

jt_2002_ta

iTrader: (3)

yes it is tuned for a maf. ive unplugged it drove around the block and it runs the same.

hrcslam

Right. It's running like poo, and you disconnect the MAF and it still runs like poo right?

This is because your P0103 and P0102 codes are MAF low signal and high signal faults. The computer is ignoring the MAF already because of those codes. So since you already have a MAF fault the MAF is already ignored in the ECM and it's already in SD mode. This mean physically disconnecting it at this time does nothing to change how the computer is operating.

Have you looked for bad grounds yet? Your MAF, Air Pump, and Injectors can all share the same grounding point. Maybe you have a loose ground somewhere.

jt_2002_ta

iTrader: (3)

yes. any idea where they ground at?

hrcslam

No, unfortunately. Hopefully someone else will chime in. Or you can move this to the Gen III External or internal mods section for people that have more experience with the wiring of the LS1 in an F-Body.

I'd check every ground from the engine to the harness to the chassis for tightness. If they are all tight, check for corrosion, is no corrosion, remove each ground connection 1 by 1 clean to bare metal and reconnect. Keep going until all grounds are good and clean or the symptoms go away.

jt_2002_ta

iTrader: (3)

does anyone know where the injectors ground at?

jt_2002_ta

iTrader: (3)

update: i had a new racetronix pump to put in so i installed it and the first few starts and a couple block drive the power was back and the a/f cleared up. now same thing again. any ideas why the new pump would of helped for a bit and now its not? ive checked harness plugs they got about 12v at the plug, injectors are at 12.4ohm which is kinda low but within spec? whats next to do, a noid light?

hrcslam

Do a fuel pressure check.

jt_2002_ta

iTrader: (3)

key on 50 psi. idle its bouncing between 60-70psi and wot and throught rpm range is steady at 60psi.

hrcslam

That's good fuel pressure. How'd the pressure look when it started running rough?

I think you need to throw a new MAF in there. If that fixes your power problems then it's a tuning issue with your VE tables.

Is your AIR pump still installed?

jt_2002_ta

iTrader: (3)

fp as soon as it started was 60-70 bouncing around. didnt climb, straight there. i swapped my trucks maf and still no change. no air pump was removed and i thought codes were tuned out which is weird. i havent had any issues untill now since it was tuned 8000 miles ago. could the pcm be going haywire?

hrcslam

If a known good MAF is causing the same problems then I'd still be looking for a ground. I'm sorry I'm not much help here. PCM could be an issue, but that is very rare. Have you done a spark check with a spark checker and compression check yet?

jt_2002_ta

iTrader: (3)

No I havent done a spark test yet. Im gonna go to harbor freight and get a tester. Havent done a compression test either. I dont think its compression related but I guess could be. Intermentntly it runs great which in theory a bad ground is very possible. I guess I need to find where all the grounds are and go from there

jt_2002_ta

iTrader: (3)

just to update the thread, one of the injector harness plugs was bad and not connecting to the injector good(i double checked those and somehow didnt notice it). p0200,p0103 and p0418 fixed from the injector plug problem. still got the p0102 but im pretty sure i can get it cleared up. thanks for the help on this hrcslam.

hrcslam

I wasn't much help, LOL.

Did you try wiping the codes and see if the Low MAF circuit stays away? Maybe another loose connection?