19 replies to this topic

[TRACStar]

I posted a few days ago about a power loss over 4K rpm. I thought originally that it may have been my FPR but I checked it today and it has good pressure while at idle, although after I shut the car off pressure drops to nothing Does this mean that my FPR is indeed bad?

If not has anyone ever experienced this power loss before?

Its definatly not fuel cut cause I hit that before and its no where near as harsh.

[lextildeath]

Well if FPR= fuel pressure regulator, then I gotta say since it is electronically fuel injected, there will be no fuel pressure with the ignition off. Carbeurated cars, however, you have to give it gas when you start it because it is a manual fuel pump. Hopefully some one who knows more will chime in, but I hope I can help.

[TRACStar]

Well if FPR= fuel pressure regulator, then I gotta say since it is electronically fuel injected, there will be no fuel pressure with the ignition off. Carbeurated cars, however, you have to give it gas when you start it because it is a manual fuel pump. Hopefully some one who knows more will chime in, but I hope I can help.

But I think that the fuel rail should still hold pressure after shutdown, maybe bleed off eventually but not right away

[kenhoeve]

place a gauge on the end of the fuel rail and monitor pressure while you rev. you should be around 42 while you have high revs, if lower you have a delivery problem.

[1997850T5R]

place a gauge on the end of the fuel rail and monitor pressure while you rev. you should be around 42 while you have high revs, if lower you have a delivery problem.

Well, I can't disagree as I'm not sure about the pressure on our cars but... Mine doesnt have any noticable fuel problems, but when I bleed the rail to remove lines to do maintenence I can tell its much lower than 40's. My former car had the same kind of bleed cap on the fuel rail, and would shoot fuel quite powerfully and at some distance when bled. The bleed off on my car only seemed to be at about 5-10psi when I bled it.

[850-Turbo]

I posted a few days ago about a power loss over 4K rpm. I thought originally that it may have been my FPR but I checked it today and it has good pressure while at idle, although after I shut the car off pressure drops to nothing Does this mean that my FPR is indeed bad?

If not has anyone ever experienced this power loss before?

Its definatly not fuel cut cause I hit that before and its no where near as harsh.

I think the fuel pressure comes from the fuel pump. The FPR only regulates the pump pressure down to managable level. Sounds like yours is regulating.

One possibility might be that at high loads, the pump may not have the volume to keep up with the demands.

Are you just not able to rev above 4K RPM, even sitting in park? How does it perform going up a hill? Would it have difficulty climbing even at 3K?

Important question is this: when you loose power, is the engine running smoothly, or is it misfiring/sputtering and rough? Roughness may indicate fuel or ignition problem. If smooth, this may indicate plugged-up exhaust.

[kenhoeve]

Well, I can't disagree as I'm not sure about the pressure on our cars but... Mine doesnt have any noticable fuel problems, but when I bleed the rail to remove lines to do maintenence I can tell its much lower than 40's. My former car had the same kind of bleed cap on the fuel rail, and would shoot fuel quite powerfully and at some distance when bled. The bleed off on my car only seemed to be at about 5-10psi when I bled it.

Our cars use a 3 bar regulator, so 42 psi is about right. Do what I said and see what happens.

[TRACStar]

there is no sputtering. Its a smooth power loss like the car just runs out of steam.

it keeps climbing in rpm's but slows down drasticly

[850-Turbo]

there is no sputtering. Its a smooth power loss like the car just runs out of steam.

it keeps climbing in rpm's but slows down drasticly

Are you saying that the engine RPM keeps going up, but the speed of the car won't go up? If this is true, your clutch is slipping if you have manual trans, or in the case of automatic trans, all I can say is transmission rebuild. Sorry, I'm not familiar with automatic transmissions.

But if what I'm understanding is not what you're saying, then I'm confused. Maybe we need more hints.

by the way, you can't have power loss and RPM climbing at the same time, so are you ,maybe, mistaking power loss with loss of speed?

[TRACStar]

Are you saying that the engine RPM keeps going up, but the speed of the car won't go up? If this is true, your clutch is slipping if you have manual trans, or in the case of automatic trans, all I can say is transmission rebuild. Sorry, I'm not familiar with automatic transmissions.

But if what I'm understanding is not what you're saying, then I'm confused. Maybe we need more hints.

by the way, you can't have power loss and RPM climbing at the same time, so are you ,maybe, mistaking power loss with loss of speed?

Rpm's do keep climbing and speed increases. Its that once the rpm's get to a certain point the car dosen't slow down, it just stops pulling hard

I'll try to get a camera tomorrow and take a short vid

Edited by 850T_Wagon, 19 March 2006 - 08:05 AM.

[bloc]

Are you saying that the engine RPM keeps going up, but the speed of the car won't go up? If this is true, your clutch is slipping if you have manual trans, or in the case of automatic trans, all I can say is transmission rebuild. Sorry, I'm not familiar with automatic transmissions.

But if what I'm understanding is not what you're saying, then I'm confused. Maybe we need more hints.

by the way, you can't have power loss and RPM climbing at the same time, so are you ,maybe, mistaking power loss with loss of speed?

actually you can.
(cue hypothetical situation)
if it takes 10 minutes to get from 4000 rpms to 5000 rpms, but only 30 seconds to get all the way to 4000, he's experiencing power loss. at least when compared to almost any other 85xT


if it's running smoothly but out of steam, and not making an weird noises, i'm going to back up the plugged exhaust theory.


normally this would be easy to test, but since the cat is integrated into the downpipe it's going to be difficult. the cat is likely what is wrong, if it's a plugged up exhaust.
one thing you can do to test this is unhook the rest of the exhaust and look into the back end of the cat to see if it's broken up.

[TRACStar]

actually you can.
(cue hypothetical situation)
if it takes 10 minutes to get from 4000 rpms to 5000 rpms, but only 30 seconds to get all the way to 4000, he's experiencing power loss. at least when compared to almost any other 85xT
if it's running smoothly but out of steam, and not making an weird noises, i'm going to back up the plugged exhaust theory.
normally this would be easy to test, but since the cat is integrated into the downpipe it's going to be difficult. the cat is likely what is wrong, if it's a plugged up exhaust.
one thing you can do to test this is unhook the rest of the exhaust and look into the back end of the cat to see if it's broken up.

I'll check that today, the cat was changed (so i was told) 500 miles before i purchased the car. It has the factory downpipe but the stock cat was cut off and a replacement (shorter) cat was put in

Maybe it just had trouble keeping up with the flow now that i'm chipped and since changing to samco's no longer losing boost

[850-Turbo]

actually you can.
(cue hypothetical situation)
if it takes 10 minutes to get from 4000 rpms to 5000 rpms, but only 30 seconds to get all the way to 4000, he's experiencing power loss. at least when compared to almost any other 85xT

Well, am I sh*t faced! You are so correct. I was only thinking of the case when driving at constant speed where loosing power, then, will only decrease in speed. Clearly, we are talking about acceleration...duh...

[bloc]

I'll check that today, the cat was changed (so i was told) 500 miles before i purchased the car. It has the factory downpipe but the stock cat was cut off and a replacement (shorter) cat was put in

Maybe it just had trouble keeping up with the flow now that i'm chipped and since changing to samco's no longer losing boost

it is possible that the chip increased flow and heat through the exhaust enough that if they used a cheap cat it killed it quickly. i drove a turbo rx7 for a while and basicly beat the crap out of that car for months, but only when i put a downpipe in, and increased the boost 5 pounds, did the cat die. within 150 miles. it went from pulling on LT1 camaros to getting stomped by geo metros. pretty dramatic difference. so i just gutted the cat and that was that.

[TRACStar]

checked the cat today and no problem there.

Drove the car with the windows down and in first gear the rpm's climb to about 3k or 3500 and then it stops pulling as hard and right before the car shifts I can hear popping in the exhaust.

Could it be spark blowout with them symptoms?

[850-Turbo]

checked the cat today and no problem there.

Drove the car with the windows down and in first gear the rpm's climb to about 3k or 3500 and then it stops pulling as hard and right before the car shifts I can hear popping in the exhaust.

Could it be spark blowout with them symptoms?

Try this test: in Park, have someone rev the engine and you feel the exhaust at the tail pipe with your hand. The exhaust should have some good pressure against your hand. If it feels whimpy, you may still have some blockage in the pipes.

[TRACStar]

Try this test: in Park, have someone rev the engine and you feel the exhaust at the tail pipe with your hand. The exhaust should have some good pressure against your hand. If it feels whimpy, you may still have some blockage in the pipes.

did that too, good pressure at the tail pipe

After hearing the popping in the exhaust today I am thinking it may be ignition related

it almost sounds like I'm shootin flames

[Account_Deleted_T5M]

Rpm's do keep climbing and speed increases. Its that once the rpm's get to a certain point the car dosen't slow down, it just stops pulling hard

I'll try to get a camera tomorrow and take a short vid

I have the exact same problem.... ODB 2 says it's o2 sensors

[bloc]

what is your boost gauge doing when this is happening?

[TRACStar]

what is your boost gauge doing when this is happening?

Boost is fine from what I can tell (factory gauge)