MotoX178

I am having a few problems with my new set up on my 94 camaro z28 a4. It is a 355 with a cc306 and mods listed in sig. The car has a hard time starting cold and a very hard time starting after it is warmed up. Around 2000-3000 rpm it has a shutter/hesitation, very aparent at high way speeds. I pulled a plug today and it appears it is also running very lean, tan/white color on plug. A few people suggested it was not getting enough fuel so I put in a walbro 255 and nothing changed. I have checked the vacuum lines and they are hooked up and I do not see any cracks in them. The plug wires are new with maybe 500 miles on them, the plugs are new, and I have a MadZ tune. After it warms up and I drive it for about 10 minutes it likes to die at stop lights and such, it died today after sitting at a stop light as I pulled away. It will not restart after it dies on its own, you have to wait a few minutes then crank it over and give it a little throttle. It runs fine at high RPMs. I have run out of ideas, the only thing that is old it the Opti, the new one I put on was actually bad so while I am waiting for the warranty replacement to come in I have my old one on there. Could this be the problem? I have done a lot of searching and reading and can not find an answer. Before I start spending a lot of money I want to make sure it is on the right parts.

Here is the datalog, it is a little long.

http://www.savefile.com/files/886535

I think I covered everything, I can try to get any other readings that will help as well. I have just run out of ideas and have tried reading the data log but just don't know enough yet to be able to read it. Thanks guys.

Executioner2k5

where did you get the datamaster stuff from and will it work for an OBDII car?

Injuneer

TTS DataMaster is only for 93-95 OBD-I. Nice highjack

http://www.ttspowersystems.com/

Injuneer

Have you ever checked the fuel pressure? That would have told you if you were getting enough fuel supplied. Do you have a stock fuel pressure regulator or an AFPR? If AFPR, what pressure is it set at? Pulse width and duty cycle look fairly low at WOT.

The problem appears to be mainly on the right side. The long term corrections (BLM's) are near maximum in several cells:

16 L-129 R-156
3 L-126 R-151
6 L-130 R-145
9 L-123 R-16-
13 L-132 R-154

Then there are some oddball Cells:

10 L-132 R-124
14 L-130 R-128
15 L-129 R-129

When was the PCM "cleared" last? Just before this data log?

Idle is unstable, MAP is all over the place, ranging from 56 - 81kPa, with an average of 65kPa. Misfires, sticky valves, incorrect valve adjustment could account for that.

Idle it not well controlled. Programming is set for 900RPM target, but it ranges from 675 - 1275 RPM with an average of 1000RPM. IAC counts are high at 77, but that's not unusual with a decent cam. Air flow GPS seems on the high side, but that may be the result of the excessive idle speed. Your coolant at idle is 210*F. Might be worth a 160* t'stat and fan on/off temp reprogramming. If you already have that, the radiator isn't working too well.

I found three WOT pulls, and the O2 levels look low on the last one - but stock O2 sensors are not all that good for measuring WOT A/F. The left side looks leaner than the right, and on the low side (only at times), 840-860 range mV's. The right side is typically 40mV higher. Seems odd, when the BLM's are both 129 in Cell 15.

MotoX178

The PCM was cleared before this datalog, I had a few error codes after the first few miles on the motor they were:

code 36 hi-res failure
code 41 est open
code 42 est grounded
code 51 prom/flash error

I cleared them and the only code I got after that was about the AC pressure. The other day it threw two codes:

code 46 fuel enable failure
code 51 prom/flash error

I cleared those again. I am going to re-check the valve adjustments today, anything else I should take a look at? Could one sensor going bad cause this much of a problem? I will also try to get a read out on the fuel pressure, I just cant find a store that sells a guage. Thanks you for the help I am just use to single cylinder dirt bikes.

Injuneer

DTC 46 is for the Pass-Key security system (which does eventually affect the fuel pump signal).

One suggestion.... don't reset the computer before a data log. It erases the long term fuel corrections, and if you don't have a lot of driving over a wide range of engine loads and RPM, it keeps you from knowing what the long term corrections are for all the Cells.

Have you looked this over:

http://members.aol.com/InjuneerZZ/ScanMast.htm

MotoX178

Thanks for the link, I haven't seen that one before. It is very helpful in understanding the engine system. I haven't had time to finish reading it yet, but do you think my problems are mechanical, sensor or tune related? I have an opti coming in this week I hope, and I am going to pick up a fuel pressure guage tomorrow.

MotoX178

Thanks for the help Injuneer. I recieved my replacement opti in this week and re-checked the valves, now the engine runs very well. The other opti had a crack in it so I am thinking that has something to do with my problems.

Injuneer

Thanks for the feedback. As you can see from my signature, not everyone is happy with my attempts to help