HELP! Master troubleshooter needed! Injuneer, Shoebox, anybody!
Thread Starter
Registered User
Joined: Apr 2002
Posts: 124
From: Milwaukee, WI
Originally posted by OutKast
Possibly a bad fuel pressure regulator - Have you checked the pressure on the rail? This could cause your rich condition
Possible bad MAP sensor - if it's at all faulty, the computer will not calculate fuel correctly. The 93's are more sensitive to bad MAPs since we don't use a MAF to measure how much air is comming in.
Send me your DM files and I'll have a quick look for you.
Possibly a bad fuel pressure regulator - Have you checked the pressure on the rail? This could cause your rich condition
Possible bad MAP sensor - if it's at all faulty, the computer will not calculate fuel correctly. The 93's are more sensitive to bad MAPs since we don't use a MAF to measure how much air is comming in.
Send me your DM files and I'll have a quick look for you.
Map sensor was checked, from atmosphere to full vacuum, readings were in line with service manual, I will re-check to post some data.....
Administrator
Joined: Nov 1998
Posts: 71,098
From: Hell was full so they sent me to NJ
It isn't an issue of whether the MAP sensor is working correctly. All you are doing by testing output vs. vacuum is whether the sensor is healthy. But if you only have 10"Hg vacuum, your MAP readings at idle are way too high. MAP = BAR - vacuum. I suspect you are getting 65-70kPA at idle (20"Hg) MAP readings. That is way too high.
The question is why?
The question is why?
Thread Starter
Registered User
Joined: Apr 2002
Posts: 124
From: Milwaukee, WI
Originally posted by Injuneer
I can only look at the DataMaster files if you have them in .csv format. I can give you an e-mail address to send them, if they are in that format.
The things that stand out are the irrational values you get with the timing light (you should only see 18-20deg at idle , and yes, there is no reason you should see 60-deg), the 10"Hg vacuum, and the 160 IAC count. Have you checked the valve adjustment? Have you verified lift on the cam (badly worn lobes)?
Maybe I missed it in your list, but have you ever done a compression and/or leakdown test?
I can only look at the DataMaster files if you have them in .csv format. I can give you an e-mail address to send them, if they are in that format.
The things that stand out are the irrational values you get with the timing light (you should only see 18-20deg at idle , and yes, there is no reason you should see 60-deg), the 10"Hg vacuum, and the 160 IAC count. Have you checked the valve adjustment? Have you verified lift on the cam (badly worn lobes)?
Maybe I missed it in your list, but have you ever done a compression and/or leakdown test?
Plus I asked very specifically, did he have ANY driveability/loss of power problems leading up to these incidents, and he said no...But, of course I'm willing to try ANYTHING to get this car running?
Anybody think dropping the cats & running open exaust to check for plugged cats is worth a try?
Registered User
Joined: Oct 1998
Posts: 226
From: Raleigh, NC
Fuel Injectors clogged with something? I've seen a clogged cat on another camaro and it started fine....after a few mins, then the idle speed would decrease, and then car would barely go over 45mph.
Doug
Doug
Thread Starter
Registered User
Joined: Apr 2002
Posts: 124
From: Milwaukee, WI
Originally posted by Injuneer
It isn't an issue of whether the MAP sensor is working correctly. All you are doing by testing output vs. vacuum is whether the sensor is healthy. But if you only have 10"Hg vacuum, your MAP readings at idle are way too high. MAP = BAR - vacuum. I suspect you are getting 65-70kPA at idle (20"Hg) MAP readings. That is way too high.
The question is why?
It isn't an issue of whether the MAP sensor is working correctly. All you are doing by testing output vs. vacuum is whether the sensor is healthy. But if you only have 10"Hg vacuum, your MAP readings at idle are way too high. MAP = BAR - vacuum. I suspect you are getting 65-70kPA at idle (20"Hg) MAP readings. That is way too high.
The question is why?
Would it be worth-while to buy a spark checker and check spark output more qualitatively?
WHy does the datamaster show an injector #1 AND #2 fault?
I also noticed that the knock counts were counting like crazy.....But the ignition did not (appear) to retard.....
Taction control was not active...
I turned of the lights in the garage & did not see a light show....
Thread Starter
Registered User
Joined: Apr 2002
Posts: 124
From: Milwaukee, WI
O.K. Here's an update:
Went out tonight, and removed the fuel rails..Inspected the injectors, physically they looked good. RE-connected fuel lines, and pressurized the fuel rail. No injectors were dripping.
Held injectors over holes and cranked engine, all the injectors were firing evenly. Put new o-rings on and replaced assembly.
Started car & idled. Put an o-scope on the lo-res and hi-res signals from the opti-crap.
The high-res was evenly spaced, nice & clean signal. The lo-res had the 4 various length pulses and the overall signal looked clean.
Checked the output of the ECM to the ICM module, again, signal looked extremely clean.
Re-checked timing with timing light: appears to be ~ 30 deg idle. Jumps to ~55 when gas is given ??
By oscillating the throttle, I can get the car to rev to 2500 RPM. Timing was at ~30 degrees @ 2500 rpm.
Car backfires after letting off the gas....
I cut the car off. I noticed that the exhaust manifolds (BOTH) were CHERRY RED.....
WHat does this mean???
Where should I go next???
Went out tonight, and removed the fuel rails..Inspected the injectors, physically they looked good. RE-connected fuel lines, and pressurized the fuel rail. No injectors were dripping.
Held injectors over holes and cranked engine, all the injectors were firing evenly. Put new o-rings on and replaced assembly.
Started car & idled. Put an o-scope on the lo-res and hi-res signals from the opti-crap.
The high-res was evenly spaced, nice & clean signal. The lo-res had the 4 various length pulses and the overall signal looked clean.
Checked the output of the ECM to the ICM module, again, signal looked extremely clean.
Re-checked timing with timing light: appears to be ~ 30 deg idle. Jumps to ~55 when gas is given ??
By oscillating the throttle, I can get the car to rev to 2500 RPM. Timing was at ~30 degrees @ 2500 rpm.
Car backfires after letting off the gas....
I cut the car off. I noticed that the exhaust manifolds (BOTH) were CHERRY RED.....
WHat does this mean???
Where should I go next???
Registered User
Joined: Mar 2000
Posts: 129
From: British Columbia, Canada
My thoughts, for what they are worth, is that you need to ignore all that has been done, and diagnose with a clear head.
I may have missed it, but do you have any O2 sensor data?
Also, have you confirmed that the timing chain has not jumped a tooth?
Good luck, it can and will be fixed, because as they say, "its just metal...."
I may have missed it, but do you have any O2 sensor data?
Also, have you confirmed that the timing chain has not jumped a tooth?
Good luck, it can and will be fixed, because as they say, "its just metal...."
Registered User
Joined: Dec 1969
Posts: 27,727
From: Little Rock, AR
Red manifolds, IMO takes it back to too much fuel. The excess fuel is burning outside the head when it hits the manifolds. As I said before, the MAP is way high. The pcm would consider this a high load and likely add the fuel. Gotta figure out if the sensor is the problem or something is causing it to read like it is.
How about a test to fake out the sensor?
Do you have a Mityvac or similar? Remove the MAP sensor and plug the hole in the manifold. Apply about 20" of vacuum to the sensor with a hose and your Mityvac. Crank it up and see what happens. Can you monitor it with Datamaster when you do this?
How about a test to fake out the sensor?
Do you have a Mityvac or similar? Remove the MAP sensor and plug the hole in the manifold. Apply about 20" of vacuum to the sensor with a hose and your Mityvac. Crank it up and see what happens. Can you monitor it with Datamaster when you do this?
Last edited by shoebox; Oct 8, 2003 at 09:22 PM.