Cascade Crew

aaron_sK

Still trying to track down this rich idle problem. Pulled the rail and pressure tested the injectors. All nine of them are solid. Not a drop hit the pan.

What else is going to cause a drop in fuel pressure? Tank check valve? Pressure regulator? Could either of those cause it to run way to rich?

Dewey316 · Posted: Thu Sep 06, 2007 2:45 pm Post subject:

temp sensor?

aaron_sK · Posted: Thu Sep 06, 2007 2:53 pm Post subject:

Would that keep it out of closed loop at all? Blinked the SES light and it appears to be hitting closed loop.

Dewey316 · Posted: Thu Sep 06, 2007 2:58 pm Post subject:

it depends, if it is unplugged, it will throw a code. If it is just bad, it might not, but it might think the car is at like -20*, and dump in fuel to compensate for the temp.

Do you have a scan tool?

aaron_sK · Posted: Thu Sep 06, 2007 3:19 pm Post subject:

Not for this car. I had always figured on buying a cheapo CL laptop, and then running an ALDL cable. I'm thinking it would probably be a good idea to get that going before I spend any more cash replacing parts.

Dewey316 · Posted: Thu Sep 06, 2007 3:20 pm Post subject:

Can you rent them for nothing/almost nothing at a local parts store? Might be worth making a call, all you really need to see is what the scanner is howing the coolant temp is reading.

BigDaddyVu · Posted: Thu Sep 06, 2007 3:44 pm Post subject:

initial timing, improper fuel pressure to injectors, o2 sensor, egr sensor, spark plug condition (heat range). these small factors can add up.

Raiden · Member Joined: 10 Mar 2004 Posts: 193 Location: tacoma

what is the fuel psi? I wonder if the fuel pressure diaphram is torn a tiny bit. That is a frequent cause of a rich idle and dropping fuel psi.

aaron_sK · Posted: Mon Sep 10, 2007 1:17 pm Post subject:

I pulled the AFPR and diaphram last month and it looked fine, but I can't say for sure after that.

This weekend I worked on it again. Put in another new O2 sensor, new coolant temp sensor, new plenum and tb gaskets, manually lowered the idle RPM's from 800 to 500 (the screw was adjusted previously, so it wasn't stock), and unplugged the cold start system. Tested it again and idle HC dropped from 760 to 305. I fixed something, but it's still not right.

Drove home and it was idling like sh**. Checked the fuel pressure and it was about 28psi at idle. Pulled off the vacuum line and it jumped to around 38psi. That morning I had checked it and it was at it's normal 38 idle, 46 w/no vacuum.

The adjust screw on the AFPR does nothing to the pressure at all, so either the AFPR is bad, or the pump is bad. Either way it's parked yet again.

Dewey316 · Posted: Mon Sep 10, 2007 1:27 pm Post subject:

I would toss a diffrent FPR on, and see what it does.

Raiden · Member Joined: 10 Mar 2004 Posts: 193 Location: tacoma

If it's not your fuel pressure regulator, I would highly suspect the pump. I'm not sure if there's a way to check the fuel pump? When the psi regulators go, they usually GO! you may want to change your fuel filter, it could be plugged up causing low pressure in the system.

DBL_TKE · Posted: Wed Sep 12, 2007 12:14 am Post subject:

did you check your cold start injector as well?

aaron_sK · Posted: Wed Sep 12, 2007 9:29 am Post subject:

Yeah, I pressure tested it along with the rest of the rail. No leakdown. I pulled the harness off of the injector and the sensor, so the entire system is disabled anyway.

91RSVert · Posted: Wed Sep 12, 2007 9:46 am Post subject:

If his fuel pump is bad, or filter is clogged, wouldnt that cause a lean condition as its not getting ENOUGH fuel?

But low pressure, bad FPR, bad filter, bad pump, or the hose in the tank cranked.

Rich idle... not enough spark, leaky injectors(tested), vac leak causing map/maf to not read right, idle module bad(having brain fart on the name of that thing), valve not opening right, cam lobe rounded off.

Have you checked it with a vac guage?

aaron_sK · Posted: Wed Sep 12, 2007 10:24 am Post subject:

I honestly think it's two sepperate problems, as I was having the rich idle issue long before the fuel pressure started dropping off.

Vacuum reads about 18hg at idle, but it varies slightly. It's not rythmic like a bad valve, it's slower. Tested it at the brake booster, the throttle body, and the FPR fitting, all tests came back the same. Throttle snap drops and comes back up fine.