I'm stumped-Is the motor gone??
05-07-2009, 12:49 PM
#1
I'm stumped-Is the motor gone?? I will try and make a long story short from my last track outing late last year. Now I am trying to fix the problem but I'm totally stumped. The head gaskets were done a month before this and was running great up until the vacuum line came off the alky system. I really don't want take the heads off again.
So here it is:
The vacuum hose that goes to my 2 bar MAP sensor that runs my alky system had popped off. I made a run through 4 gears at WOT with no alky on a tune that relies on it. Massive lean condition and the IATs didn't move lower at all. 14-1 at the begging of a gear and 12.5-1 by 6K where I shift. Massive knock counts all through the run. Needless to say there was lots of detonation.
The bad:
Mechanical wise the headers tubes 2,3,4,5,6 and 8 get red hot and glow after 4 minutes of running and I have lost 2 HG of vacuum. It idles fine on its own after you open up the throttle blades to get the RPMs up.
It is running SUPER rich, plugs get wet with fuel after a few minutes of running…causing glowing headers.
It idles fine in open loop but goes to **** in closed loop where I have to shut it off as the headers are red-red.
The good:
Idles fine in open loop.
No knocking noises when at idle or blipping the gas.
No ticking from the valve train .
No coolant in the cylinders or the ground. Still in the rad.
Oil and filter were changed and checked out good, no metal on the oilpan magnet.
Oil pressure is solid.
Coolant temp is fine.
No puff puff from the valve cover breather indicating there is no blow by from the rings
Did a compression test.
Results in PSI:
#2 165 #1 175
#4 175 #3 175
#6 170 #5 175
#8 165 #7 170
Keep in mind this is an 8 year old 9:1 blower engine.
A leakdown test was done on the first 4 cylinders. The easy ones were done including one of the 165psi compression holes.
Results were 10 for all holes with no air escaping from the valves and a shade from the rings. To be expected from such an old motor.
From the logger I see:
Before lean ++ After lean
MAP 50-52 ++ 65-67
IAC 55 ++++maxed at 160
MAF air flow grams/sec
10-11+++ 16-17
Base pules widths
1.4-1.5 +++2.4-2.5
INJ DC
1 ++++1.6-1.7
The BLMs looked good from the few secs it went into closed loop. No codes either
Conclusion:
It is running way rich and the plugs were soaked in fuel. The PCM is seeing lots of air come in for some reason. The MAP is high (confirms loss of 2 hg on boost guage) and I *think* it thinks the car is under load and commanding fuel to equal the (wrongly calculated) air. That is one theory anyway but why??
Why this would happen right after it went lean at the track? I don't see how anything mechanical could cause this unless there is a leak somewhere that I am not seeing. It seems the engine is OK though.
With a vacuum leak I've always seen the BLMs go green for a lean condition (uncompensated air) which I am not getting this time around. No codes either and it doesn’t high idle like you have with most intake leaks. The BLMs look good for the few minutes I let it go closed loop. I looked for intake leaks, sprayed contact cleaner on the IAC and TPS connectors, cleaned the throttle body, reconnected the Crane box and a few other things. No dice.
Any ideas?? I am stumped and don’t want to pull the heads anytime soon. I am thinking a huge intake leak or a bunch of bad valves in a bunch of cylinders…bent pushrods??
People are pointing the finger at the old stand-by opti and to replace all the sensors. I think they are reading correctly and detonation wouldn’t kill a bunch of different sensors all at the same time.
So here it is:
The vacuum hose that goes to my 2 bar MAP sensor that runs my alky system had popped off. I made a run through 4 gears at WOT with no alky on a tune that relies on it. Massive lean condition and the IATs didn't move lower at all. 14-1 at the begging of a gear and 12.5-1 by 6K where I shift. Massive knock counts all through the run. Needless to say there was lots of detonation.
The bad:
Mechanical wise the headers tubes 2,3,4,5,6 and 8 get red hot and glow after 4 minutes of running and I have lost 2 HG of vacuum. It idles fine on its own after you open up the throttle blades to get the RPMs up.
It is running SUPER rich, plugs get wet with fuel after a few minutes of running…causing glowing headers.
It idles fine in open loop but goes to **** in closed loop where I have to shut it off as the headers are red-red.
The good:
Idles fine in open loop.
No knocking noises when at idle or blipping the gas.
No ticking from the valve train .
No coolant in the cylinders or the ground. Still in the rad.
Oil and filter were changed and checked out good, no metal on the oilpan magnet.
Oil pressure is solid.
Coolant temp is fine.
No puff puff from the valve cover breather indicating there is no blow by from the rings
Did a compression test.
Results in PSI:
#2 165 #1 175
#4 175 #3 175
#6 170 #5 175
#8 165 #7 170
Keep in mind this is an 8 year old 9:1 blower engine.
A leakdown test was done on the first 4 cylinders. The easy ones were done including one of the 165psi compression holes.
Results were 10 for all holes with no air escaping from the valves and a shade from the rings. To be expected from such an old motor.
From the logger I see:
Before lean ++ After lean
MAP 50-52 ++ 65-67
IAC 55 ++++maxed at 160
MAF air flow grams/sec
10-11+++ 16-17
Base pules widths
1.4-1.5 +++2.4-2.5
INJ DC
1 ++++1.6-1.7
The BLMs looked good from the few secs it went into closed loop. No codes either
Conclusion:
It is running way rich and the plugs were soaked in fuel. The PCM is seeing lots of air come in for some reason. The MAP is high (confirms loss of 2 hg on boost guage) and I *think* it thinks the car is under load and commanding fuel to equal the (wrongly calculated) air. That is one theory anyway but why??
Why this would happen right after it went lean at the track? I don't see how anything mechanical could cause this unless there is a leak somewhere that I am not seeing. It seems the engine is OK though.
With a vacuum leak I've always seen the BLMs go green for a lean condition (uncompensated air) which I am not getting this time around. No codes either and it doesn’t high idle like you have with most intake leaks. The BLMs look good for the few minutes I let it go closed loop. I looked for intake leaks, sprayed contact cleaner on the IAC and TPS connectors, cleaned the throttle body, reconnected the Crane box and a few other things. No dice.
Any ideas?? I am stumped and don’t want to pull the heads anytime soon. I am thinking a huge intake leak or a bunch of bad valves in a bunch of cylinders…bent pushrods??
People are pointing the finger at the old stand-by opti and to replace all the sensors. I think they are reading correctly and detonation wouldn’t kill a bunch of different sensors all at the same time.
