At what psi should normal compression be at idle? Because my bud is getting me the compression test tool, and for some reason I want to 30PSI at idle is this right? And would a reding too low/high be a sign of a bad fuel pressure regulator which I have been told is my problem of running so rich at WOT.
Fuel Compression results
- Thread starter RI-SHO
- Start date
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twr
whoohoo
You're talking fuel pressure right?? With the vacuum hose disconnect from the fuel pressure regulator and plugged you should get 39psi.
<small>[ August 22, 2002, 06:09 PM: Message edited by: twrsho ]</small>
<small>[ August 22, 2002, 06:09 PM: Message edited by: twrsho ]</small>
naval-avi8or
New Member
Here's the proper testing procedure and parameters for the fuel pressure test.
Testing and Inspection
WARNING: Before servicing or replacing any components in the fuel system, reduce the possibility of injury or fire, refer to Service Precautions .
Key Off.
Before releasing fuel system pressure at the schrader fitting, observe the Service Precautions to avoid fuel spillage and injury.
Install the fuel pressure tester.
Diagnostic Connector
Ground the fuel pump lead of the Diagnostic Connector with a jumper.
Key On, Engine Off to operate the fuel pump.
Verify that the observed fuel pressure is within specified limits.
Specifications:
Key On Engine Off 240-310 kPa (37-43 PSI)
Key On Engine Running (Idle Speed) 240-310 kPa (35-45 PSI)
NOTE: Maximum fuel pressure is obtainable with the vacuum hose removed from the fuel pressure regulator or at Wide Open Throttle (WOT).
<small>[ August 21, 2002, 08:11 PM: Message edited by: naval-avi8or ]</small>
Testing and Inspection
WARNING: Before servicing or replacing any components in the fuel system, reduce the possibility of injury or fire, refer to Service Precautions .
Key Off.
Before releasing fuel system pressure at the schrader fitting, observe the Service Precautions to avoid fuel spillage and injury.
Install the fuel pressure tester.
Diagnostic Connector
Ground the fuel pump lead of the Diagnostic Connector with a jumper.
Key On, Engine Off to operate the fuel pump.
Verify that the observed fuel pressure is within specified limits.
Specifications:
Key On Engine Off 240-310 kPa (37-43 PSI)
Key On Engine Running (Idle Speed) 240-310 kPa (35-45 PSI)
NOTE: Maximum fuel pressure is obtainable with the vacuum hose removed from the fuel pressure regulator or at Wide Open Throttle (WOT).
<small>[ August 21, 2002, 08:11 PM: Message edited by: naval-avi8or ]</small>
naval-avi8or
New Member
It could also be a fuel pump problem. Do you know if you have the correct fuel pump. Some SHO's were sent with a SLO fuel pump. Or your could be going out. Or the FPR could also just be going bad.
I dont know about the fuel pump but its original as far as I know.
BTW the pressure with KEY ON/ENGINE OFF is 35PSI.
I'll try the FPR this friday(my day off), are there any surprises awaiting me for replacing the FPR? Or just basic unbolt/bolt-on.
BTW the pressure with KEY ON/ENGINE OFF is 35PSI.
I'll try the FPR this friday(my day off), are there any surprises awaiting me for replacing the FPR? Or just basic unbolt/bolt-on.
twr
whoohoo
RI-SHO - your fuel pump and FPR are good - no need to change them.
Your getting the text book numbers, At idle you should be seeing between 30 to 32 psi (high vacuun) at WOT or the vacuum hose disconnect and plugged (low vacuum) you should get 39psi. Since you are getting these numbers, What is prompting you to believe there is a problem??
The fact that your getting 39psi with no vacuum indicates a good pump, the fuel pressure at idle is 30psi indicates a good FPR and the fact that the system hold pressure after shut down indicates a good check valve in the fuel pump.
<small>[ August 22, 2002, 06:11 PM: Message edited by: twrsho ]</small>
Your getting the text book numbers, At idle you should be seeing between 30 to 32 psi (high vacuun) at WOT or the vacuum hose disconnect and plugged (low vacuum) you should get 39psi. Since you are getting these numbers, What is prompting you to believe there is a problem??
The fact that your getting 39psi with no vacuum indicates a good pump, the fuel pressure at idle is 30psi indicates a good FPR and the fact that the system hold pressure after shut down indicates a good check valve in the fuel pump.
<small>[ August 22, 2002, 06:11 PM: Message edited by: twrsho ]</small>
I have been told to change the FPR b/c how rich I am running. I can get ppl to step away from the rear of my car just with a few check revs. Nice black puffs of smoke and gas smell(after revving) when revved hard or shifting pass 4000+RPM. Its more noticible at nite with headlights on me and me looking my rear-view mirror.
twr
whoohoo
RI-SHO,
The only way FPR is going to cause a problem like that is if you're getting 60-90 psi at the rail.
Honestly, I don't think the FPR is the problem. If you have access to a hand held vacuum pump, you can hook it to the FPR and slow apply a vacuum to it. If your fuel pressure spikes, then yes FPR is going, if drops smoothly the more vacuum you apply, then it's fine.
Are you getting any codes?? Have you cleaned your MAF sensor lately?? How old are the O2 sensors?? TPS sensor?? BAP sensor?? ACT?? There are many things that can cause this, even if the fuel pressure is slightly elevated, the EEC picks up on it by way of the O2's and adjusts for it.
You don't have an LPM or Chip, right? So there is something telling the EEC that it's getting more air than it really is. My guess is a dirty MAF, clean it only with electrical cleaner (no residue)
My 95' recently failed emmisions due to a dirty MAF, unfortunalty it cost me $75 bucks to find that out.
<small>[ August 22, 2002, 09:14 PM: Message edited by: twrsho ]</small>
The only way FPR is going to cause a problem like that is if you're getting 60-90 psi at the rail.
Honestly, I don't think the FPR is the problem. If you have access to a hand held vacuum pump, you can hook it to the FPR and slow apply a vacuum to it. If your fuel pressure spikes, then yes FPR is going, if drops smoothly the more vacuum you apply, then it's fine.
Are you getting any codes?? Have you cleaned your MAF sensor lately?? How old are the O2 sensors?? TPS sensor?? BAP sensor?? ACT?? There are many things that can cause this, even if the fuel pressure is slightly elevated, the EEC picks up on it by way of the O2's and adjusts for it.
You don't have an LPM or Chip, right? So there is something telling the EEC that it's getting more air than it really is. My guess is a dirty MAF, clean it only with electrical cleaner (no residue)
My 95' recently failed emmisions due to a dirty MAF, unfortunalty it cost me $75 bucks to find that out.
<small>[ August 22, 2002, 09:14 PM: Message edited by: twrsho ]</small>
Nope I wanna fix this problem before it breaks more sensors/plugs again. Because about 2mths ago I replaced the O2's again with Bosch and new Motorcraft plugs after the old set were fouled b/c of how much extra fuel I was getting. The old O2's and plugs were less than 8mths old and just died. I have cleaned the intake and MAF several times it starting to shine now
, so I doubt it could be that I even reset the EEC for a straight 24hrs and it ran fine till next day when the same problem came right back. I dont have any sort of chip just SS CAI/PP y-pipe/cat-back, so I doubt any of these things could affect the EEC.
So what else do you it could be if the FPR can be ruled out now?
, so I doubt it could be that I even reset the EEC for a straight 24hrs and it ran fine till next day when the same problem came right back. I dont have any sort of chip just SS CAI/PP y-pipe/cat-back, so I doubt any of these things could affect the EEC.So what else do you it could be if the FPR can be ruled out now?
twr
whoohoo
The BAP, ACT and the TPS can effect it.
When you pulled the plugs, where they all evenly fouled, or did you have one bank (or a few cylinders) running normal? I ask this as a plugged injector can often trick the the ECU into adding extra fuel to compensate leading to rich running on some cylinders.RI-SHO:
Nope I wanna fix this problem before it breaks more sensors/plugs again. Because about 2mths ago I replaced the O2's again with Bosch and new Motorcraft plugs after the old set were fouled b/c of how much extra fuel I was getting. The old O2's and plugs were less than 8mths old and just died. I have cleaned the intake and MAF several times it starting to shine now
So what else do you it could be if the FPR can be ruled out now?
Also, have your run a cylinder balance test? This might tell you if you have an injector issue.
I'm pretty sure there isnt a problem b/c last year i lost two doing 130MPH and had 3 injectors replaced. Both O2's were shot and all 6plugs were lightly fouled pretty considering they were less than a year old.
How would check to see if a bad TPS is a problem? I've read this sensor can also improve many things like idle etc.
How would check to see if a bad TPS is a problem? I've read this sensor can also improve many things like idle etc.
GreenBird
New Member
clean your MAF.
SHOTIME
Giver of life
Edien, You car has no backpressure. what do you expect.
CIA and straight through exhaust with no resonator. the more air it moves, the more gas it uses, and often doesnt burn.
CIA and straight through exhaust with no resonator. the more air it moves, the more gas it uses, and often doesnt burn.
