'91 olds 98 won't start

[maxwedge]

That is a good indication the damper should be ok. The maf disconnected should affect the engine as the pcm goes to a default setting and would not normally perform properly at a higher speed under load., I would check the maf on a scanner to see what the pcm sees for air flow. Still get a fp gage on it under operating conditions first.

[ythraccm]

OK, I tested the fuel pressure while cranking and running and also checked the scanner sensor reading.
Below is the summary of scanner readings & conditions.

Cold the IAT and CTS were 2 degrees celsius apart. Air was 20 and coolant was 22. The actual measured air temp was 25 centigrade.
Fuel pressure key on engine off = 49 psig, cranking it would drop to 47 psig, Engine running at idle was 40 psig.
After connecting scanner the engine refused to start up, it would occasionally spit out the intake.
I disconnected the crank sensor and it started up, idled rough for a few seconds and smoothed out.
Oxygen sensor reading cold engine idling 443mv. Dropped to 278mv after stopping engine and reconnecting cam sensor and clearing codes warm engine idling. Rich/ lean flag stuck at rich when warmed up.
Scanner shows open loop condition which I think is normal. It seems to run better in closed loop though.
MAF sensor when cold was reading 8 gm/sec in closed loop and dropped to 5 gm/sec when warmed up in open loop. Should be 4.9 (varies) in closed loop operation.
Engine load (LV8) was running 90-100 when cold and dropped to 60 when warmed up.
Block learn seems to run at 149 counts cold or hot. (Alldata says this indicates lean mixture).
Idle air control started out at 70 and in now down to 20 when warmed up.

the fuel integrator was 182 when engine cold and in closed loop and dropped down to 128 open loop and warm.
Spark advance was 14 degrees jumping to 9 degrees briefly at times when warmed up.
Air fuel ratio is 14.76 in closed loop cold, 14.5 in open loop mode warmed up

When the A/c is turned on, while engine is still cool and idling you can hear the intake sound getting louder before the compressor kicks in but the engine doesn't seem to pick up but instead stumbles and the sound lowers before the compressor turns off. this is repetitive like the IAC is trying to compensate for the changing load but the engine fuel isn't coming up proportionally to give it the power therefore stumbling (trying to stall out) causing compressor to turn off. Racing engine does the same thing until warm. [IMG]file:///C:/WINDOWS/TEMP/moz-screenshot-1.jpg[/IMG][IMG]file:///C:/WINDOWS/TEMP/moz-screenshot.jpg[/IMG]

[maxwedge]

Is the o2 switching as expected? I'd check engine vacuum also. You the int was 182 cold and closed loop can't be both ,cold is open loop? You say closed loop cold, this doesn't add up. You say you disconnected the crank sensor and it started?

[ythraccm]

The O2 is no longer switching. Just shows rich on the rich/ lean flag. It used to bounce back & forth before I corrected the vacuum leaks I could find. Still not sure if intake manifold isn't leaking somewhere.
The engine Vacuum was checked this morning when I checked the fuel pressure. Started OK this morning but still hunting & rough idle. Cold and idling, the vacuum was running between 15 & 16 1/2 inches. After it warmed up, the idle speed came up and steadied, it was around 18 inches.

The int was 182 and I guess it was in closed loop because the cam sensor was disconnected at the time with a code 41. And yes the engine started with cam sensor disconnected. It wasn't starting otherwise at the time. I guess closing the loop runs the engine on mempak settings in the prom.

Anyway the scanner, when I started it this morning, showed open loop and stayed open loop. Isn't open loop when the engine sensors are being monitored or is it the other way around.

[ythraccm]

The O2 is no longer switching. Just shows rich on the rich/ lean flag. It used to bounce back & forth before I corrected the vacuum leaks I could find. Still not sure if intake manifold isn't leaking somewhere.
The engine Vacuum was checked this morning when I checked the fuel pressure. Started OK this morning but still hunting & rough idle. Cold and idling, the vacuum was running between 15 & 16 1/2 inches. After it warmed up, the idle speed came up and steadied, it was around 18 inches.

The int was 182 and I guess it was in open loop because the cam sensor was disconnected at the time with a code 41. And yes the engine started with cam sensor disconnected. It wasn't starting otherwise at the time. I guess closing the loop runs the engine on mempak settings in the prom.

Anyway the scanner, when I started it this morning, showed open loop and stayed open loop. This time all sensors connected.
I found this next paragraph on the forum.
[ To clarify the above, closed loop occurs when all sensors are working and feeding data to the computer. The engine will not enter closed loop operation until the EGO sensor is warmed up - generally between 1-2 minutes of operation. In open loop, the computer discards data from certain sensors and runs a program with pre-determined levels for various conditions - generally this is not optimal and is often referred to as "limp mode". If your SES light is on, you're generally in open loop operation.]as quoted by silicon 212

The SES light never comes on even though it is in open loop. It does come on when key is turned on though and goes out when engine starts.

[tyflesh]

i do have to say that i had to replace my balancer because the rubber had dry rotted, it was giviing me a rougher idle and alot let power when driving down the road, i thought it was the timing belt, and after i continued to drive like this the rubber finally gave way, the whole time im thinking the timing chain was going out on me, didnt realize it was the balancer that had dry rotten till i got under there and was looking around the timing chain cover and the oil pan

[maxwedge]

Remember a bad o2 sensor will not allow closed loop operation, same as coolant temp sensor not tell ing the pcm the engine has reached a preset desired temp for closed loop.

[ythraccm]

I'm thinking that maxwedge has a point about the 02 sensor being out of whack, as it should be showing lean and not rich. The fact that it is showing rich may be causing it to run lean though wouldnt you think or does the 02 sensor have any effect on the fuel air mixture control? But why is it not giving me a code?

[maxwedge]

Pre obd11 systems may not set a code for this. The pcm assumes the sensor is in range and just tries to correct with the block learn, when it cannot achieve this, then it will set a code.

[ythraccm]

Since last post, I was going to check out 02 sensor further.
I went to start the car. It now has been sitting for 3 days since I last fooled with it. We are now back to the beginning. It won't start and only backfires. and wants to run backwards a stroke like very early spark timing.
Tried hitting it with starting fluid with same result. Seems the longer it sits the worse it gets starting up.
I pulled the codes using the MIL and had a new code. Code 42 which is ESTcircuit. I used alldata test procedure to check the ignition module since it seems that it is in charge of starting the engine during cranking when cold.(at least that is what I am gleaning from all this info I'm reading. Please let me know anytime I am in error) I got some out of the ballpark resistance readings.
The readings on BC7 (bypass control) should have switched to 6000 ohms to ground, I got infinite resistance instead, when I apply B+ voltage thru a test light to the PCM harness(which has been disconnected from the pcm) to BC6 which is EST control. Harness to Ignition module connector tested good continuity. Pin contacts in connector are good.
I assumed bad ignition module and went on ahead and purchased a new one. After it was installed, the engine fired right up.( Thought I had it made.HA HA) Put the scanner back on code 42 cleared engine still idling rough figuring pcm had to relearn the idle. After engine warmed up it went into closed loop and was running pretty good even though the exhaust O2 was still showing rich the rich lean flag would alternate rich to lean. A road test upon decelleration the O2 would drop down to 4 MV from 230 mv.
Aceeleration would produce some shudder until it would drop into passing gear. ( I will get more into that later).
This morning I went to start it up and back to square one again, I assume the new ignition module went bad.

[90oldsregency3800]

I think by this point. I'd just buy a new car.. but since it's someone else's, I wish you lots of luck figuring it out for him.. sorry I don't have any useful information!

Chris

[ythraccm]

I'm trying to figure out all causes of ignition module failure besides a beating on it and burning it with a blowtorch. Can a crank sensor cause an ignition module to go belly up or a bad ECM? I am also trying to move the secondary ignition leads away from the main harness which feeds the ICM and alternator, and fuel injectors. the length of wires to 2,4,6 cylinders makes it difficult.

[maxwedge]

Check for bad engine grounds, check alternator regulated output, check for any bad harness issues to and from the icm and from the crank sensor to the icm, take your time here.

[ythraccm]

Maxwedge, I am going to direct this at you since you have spent the most time with me on this problem.
I went and pulled the harmonic balancer off and sure enough, it looks like the vanes have been rubbing on the innermost sensor. It looks like the balancer was changed sometime not to long ago and the clearance wasn't set exactly right. So I am going to change it out, but I need to find a pic or detailed description of the vane settings on the balancer to make sure it is set correctly and for getting the distance setting right from the outside edge of crankshaft. I can probably use a caliper and measure the distance from the inside edge of balancer that fits on crankshaft and set the sensor accordingly.
Can you point me in the direction for finding this info?
I appreciate the help so far.

[maxwedge]

Good work so far, I could walk you thru this, but this link is better than the written word. http://autozone.com/az/cds/en_us/090...rInfoPages.htm