TransAmGT94

When i changed my spark plugs 5 were black 3 were white. Im guessing that the those 3 injectors needed to be cleaned. Later i checked the pressure at the fuel rails and it read 20psi which i am sure is low. I changed it to about 35 psi. The problem im having is last time i checked it and adjusted it i am sure it was around the 35 psi mark the only reason i can think of for it dropping is a slowly failing fuel pump does this sound about right?

Injuneer

You don't want your plugs to be "white" or "black". A normal plug should be lightly coated with a tan to gray deposit. Too white could be too lean, too black could be oil or fuel fouling.

Were the plugs similar on each bank of the engine... e.g. all the white ones on the same side, most of the black ones on the other side?

How did you test the fuel pressure - at idle, with and without the vacuum line, at WOT? Under what condition did you see 20psi? How did you raise the pressure to 35psi?

n2ceptor

Info on spark plugs... Nice pics...


www.gnttype.org/techarea/engine/plugs.html

TransAmGT94

20 psi was at idle and the three white ones came from cylinders 2,3 and 4 so no they were on different sides. They other 5 i pulled were all black. I did have a blown header gasket right before changing the plugs. I changed the pressure with a adjustable fuel pressure regulator

TransAmGT94

Another piece of info that might be helpful is the o2's read 900mv all the time they dont cycle back and forth at idle. This reading could be because I removed the egr system. When i got my mail order tune i had the cpu tuned for this change.

TransAmGT94

does any body have any ideas or any info that might help?

TransAmGT94

Ttt

Injuneer

If the O2 sensors are "stuck" at 900mV, you have a problem. It's possible its not going into closed loop. Do you have any kind of log of the data? Removing the EGR system would not cause that problem.

35pi isn't enough pressure, unless that's with the vacuum line on the AFPR. You set the fuel pressure to 43.5psi, WITHOUT the vacuum line connected. What fuel pressure did you tell your programmer you were going to run? If you didn't tell him a pressure, he normally would assume the stock 43.5psi.

TransAmGT94

I told him stock pressure the only time i saw the readings of the o2's was when the dealer had it on a scanner I havn't invested in a scanmaster yet. He told me that all the other readings were fine other than my knock sensor wasnt reading which i replaced and it fixed that, and the o2's that were staying at 900mv
What would cause them to read high? Ill recheck the fuel pressure tonight at the afpr with the vac line off

Injuneer

Its not a matter of the O2 sensors "reading high".... the problem is that in closed loop, at idle and at part throttle, they should be rapidly (~10 times per second) cycling between 0XX - 9XX mVs. If they are "stuck" on any figure, the PCM isn't working the way it should. If you've had the PCM reprogrammed, its possible they have opted for open loop operation, but in that case, you'd want to see 450mV at part load.

You might want to look at the "Air/Fuel Management" section of this writeup:

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

TransAmGT94

So the way it sounds is my pcm has been programmed to stay in open loop?

TransAmGT94

Here is a list of the sensors that i have replaced.

Map
IAC
TPS
Knock

the air pump and the egr system have been removed and the pcm was tuned by brian at pcmforless.

I didnt change the o2's because i was getting that high reading from them

I guess im going to invest in a scanmaster soon so i can give more info on my readings

TransAmGT94

Another question with that write up is it says o2's have to reach operating temp. What temp is it? Is it possible mine are not making it there? Im going to call brian and make sure he didnt program the cpu to stay in open loop. Ill post that later.

Injuneer

The required operating temp on the O2's is 600degF. You have "heated" sensors, to help them reach that temperature. Check the heater power supply circuit fuse to make sure its OK. Do you have "extensions" on the O2 sensors? These can cause problems.

It would be unusual for someone to reprogram for open loop operation, without telling you that's what they did.

TransAmGT94

The o2's are the stock ones that came on the car. no extensions either. I have left a message for brian to call me to check with him on my tune.