Do these numbers look OK?
02-22-2003, 02:46 PM
#1
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Thread Starter
Join Date: Feb 2003
Location: Los Angeles, Ca.
Posts: 11
Do these numbers look OK?
I have been having trouble with my ,91 305 TPI/700r4. It has no power at low speeds and misses and backfires under load.
I took a compression test just to make sure the problem is not mechanical, and I get the following numbers.
Cylinder----------PSI (dry)-------PSI(wet)
1------------------- 172--------------182
2--------------------180--------------190
3--------------------173--------------185
4--------------------185--------------195
5--------------------187--------------200
6--------------------180--------------191
7--------------------180--------------190
8--------------------182--------------192
The numbers do not look too bad to me. But the car keeps missing. Also the #3 plug was completely black with a cristallized coating that would crack off it. Any ideas or help as to what my problem could be. Could the TV cable or trans problems have anything to do with this? or start looking into fuel injection woes?
Appreciate any help. Thanks
Rick
PS : put in a new ignition module (no difference) and the MAP sensor voltages in the ECM check out OK.
I took a compression test just to make sure the problem is not mechanical, and I get the following numbers.
Cylinder----------PSI (dry)-------PSI(wet)
1------------------- 172--------------182
2--------------------180--------------190
3--------------------173--------------185
4--------------------185--------------195
5--------------------187--------------200
6--------------------180--------------191
7--------------------180--------------190
8--------------------182--------------192
The numbers do not look too bad to me. But the car keeps missing. Also the #3 plug was completely black with a cristallized coating that would crack off it. Any ideas or help as to what my problem could be. Could the TV cable or trans problems have anything to do with this? or start looking into fuel injection woes?
Appreciate any help. Thanks
Rick
PS : put in a new ignition module (no difference) and the MAP sensor voltages in the ECM check out OK.
02-22-2003, 05:06 PM
#2
Registered User
Join Date: Oct 2002
Location: Auburn MA
Posts: 247
First thing I would check is Fuel pressure. If that is OK, then start checking things with the ignition.
Coil, wires, cap & rotor, etc.
You should also scan your computer and see if any codes pop up. I think you can get this done at places like AutoZone.
Coil, wires, cap & rotor, etc.
You should also scan your computer and see if any codes pop up. I think you can get this done at places like AutoZone.
02-22-2003, 06:33 PM
#3
Registered User
Join Date: May 2002
Location: Kelowna,BC,Canada
Posts: 369
besides fuel pressure you should check fuel volume.
what you do is disconect the return line and put the end(motor side) into a bucket or bottle(old 1 liter oil bottle with the strip down the side to see how much fluid is in the bottle)and run the motor then watch it it should be about .5 liter for 30 seconds. if its not then your pump is not feeding your motor properly at higher rpm.
what you do is disconect the return line and put the end(motor side) into a bucket or bottle(old 1 liter oil bottle with the strip down the side to see how much fluid is in the bottle)and run the motor then watch it it should be about .5 liter for 30 seconds. if its not then your pump is not feeding your motor properly at higher rpm.
02-22-2003, 10:07 PM
#4
Registered User
Join Date: Sep 2002
Posts: 107
Originally posted by TunedPort 335
First thing I would check is Fuel pressure. If that is OK, then start checking things with the ignition.
Coil, wires, cap & rotor, etc.
You should also scan your computer and see if any codes pop up. I think you can get this done at places like AutoZone.
First thing I would check is Fuel pressure. If that is OK, then start checking things with the ignition.
Coil, wires, cap & rotor, etc.
You should also scan your computer and see if any codes pop up. I think you can get this done at places like AutoZone.
02-23-2003, 04:16 PM
#6
Registered User
Join Date: Feb 1999
Location: Springfield,OH. U.S.A.
Posts: 2,947
Sounds like an injector. Try switching the one in the cylinder with the blackened plug with one of the others and see if that plug gets blackened too. I'd almost bet money it's bad, I had this happen on my cousins' GranPrix and it even got worse after we tuned it up! Then we tried replacing the injector and we fixed it!
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