Car knocking and running lean
Thread Starter
Joined: Sep 2004
Posts: 4,894
Likes: 9
From: Tampa, FL
So after sleeping on this I've narrowed it down to a failed FPR or fuel pump. My injectors are ID 1000's and less than 3 months old so I doubt its those. I double checked the wiring harnesses on them as well and they are secure. I replaced the vacuum line going from the FPR to the IM so that's out as well.
Fuel pump primes as normal when I turn the key and the car starts so I'm leaning towards the FPR being broken. Last week after I moved the PCV line the car did run with very little problems, but the problems came back 10 times worse the very next day. That to me isn't very characteristic of an electrical problem but a mechanical problem that has deteoriated over time. Maybe having the vacuum line pinched for that period of time (a couple days) damaged the diaphram internal to the FPR?
I'm at an impass...I could spring for a FP sensor but from what I'm reading I'd have to drill and tap it into place on the fuel rail. That's a lot of time and effort just to diagnose a problem which will require more time and money to fix. Whereas if I just replace the FPR and the problem remains that only leaves the fuel pump...thoughts? Need the most cost and time effective way to fix this because my patience is super thin and I'm a couple mins away from towing it to a shop and washing my hands of it
Fuel pump primes as normal when I turn the key and the car starts so I'm leaning towards the FPR being broken. Last week after I moved the PCV line the car did run with very little problems, but the problems came back 10 times worse the very next day. That to me isn't very characteristic of an electrical problem but a mechanical problem that has deteoriated over time. Maybe having the vacuum line pinched for that period of time (a couple days) damaged the diaphram internal to the FPR?
I'm at an impass...I could spring for a FP sensor but from what I'm reading I'd have to drill and tap it into place on the fuel rail. That's a lot of time and effort just to diagnose a problem which will require more time and money to fix. Whereas if I just replace the FPR and the problem remains that only leaves the fuel pump...thoughts? Need the most cost and time effective way to fix this because my patience is super thin and I'm a couple mins away from towing it to a shop and washing my hands of it
Registered User
Joined: Dec 2006
Posts: 3,286
Likes: 0
From: Tampa, Fl
Originally Posted by spectacle,Dec 7 2009, 10:33 AM
So after sleeping on this I've narrowed it down to a failed FPR or fuel pump. My injectors are ID 1000's and less than 3 months old so I doubt its those. I double checked the wiring harnesses on them as well and they are secure. I replaced the vacuum line going from the FPR to the IM so that's out as well.
Fuel pump primes as normal when I turn the key and the car starts so I'm leaning towards the FPR being broken. Last week after I moved the PCV line the car did run with very little problems, but the problems came back 10 times worse the very next day. That to me isn't very characteristic of an electrical problem but a mechanical problem that has deteoriated over time. Maybe having the vacuum line pinched for that period of time (a couple days) damaged the diaphram internal to the FPR?
I'm at an impass...I could spring for a FP sensor but from what I'm reading I'd have to drill and tap it into place on the fuel rail. That's a lot of time and effort just to diagnose a problem which will require more time and money to fix. Whereas if I just replace the FPR and the problem remains that only leaves the fuel pump...thoughts? Need the most cost and time effective way to fix this because my patience is super thin and I'm a couple mins away from towing it to a shop and washing my hands of it
Fuel pump primes as normal when I turn the key and the car starts so I'm leaning towards the FPR being broken. Last week after I moved the PCV line the car did run with very little problems, but the problems came back 10 times worse the very next day. That to me isn't very characteristic of an electrical problem but a mechanical problem that has deteoriated over time. Maybe having the vacuum line pinched for that period of time (a couple days) damaged the diaphram internal to the FPR?
I'm at an impass...I could spring for a FP sensor but from what I'm reading I'd have to drill and tap it into place on the fuel rail. That's a lot of time and effort just to diagnose a problem which will require more time and money to fix. Whereas if I just replace the FPR and the problem remains that only leaves the fuel pump...thoughts? Need the most cost and time effective way to fix this because my patience is super thin and I'm a couple mins away from towing it to a shop and washing my hands of it
Replace the rail with a pressure gauge equiped rail and the fpr with an external one.
Why - I would end up doing all of this any way down the line and the gauge will tell you right off the bat if you fuel pump is weak.
J
Joined: Sep 2002
Posts: 1,938
Likes: 4
From: Sydney
Did you type in the battery compensation offset values that should have come with your injectors into your ECU. When you run huge injectors like that small changes in battery voltage can be a significant difference in mixture at idle if your battery comp tables are not set.
Not sure if your ECU supports it, but you can put a high resolution fuel pressure gauge onto the ECU and also put the pressure compensation tables that should have come with the injectors in as well. That way your ECU adjusts for thefuel pressure differences as well.
Not sure if your ECU supports it, but you can put a high resolution fuel pressure gauge onto the ECU and also put the pressure compensation tables that should have come with the injectors in as well. That way your ECU adjusts for thefuel pressure differences as well.
Thread Starter
Joined: Sep 2004
Posts: 4,894
Likes: 9
From: Tampa, FL
Few updates:
The lean reading on the wideband was due to a loose wastegate. The metallic sound I was hearing? Exhaust leak. Looks like one of the bolts broke off in the manifold. I'm lucky I didn't lose the WG altogether.
So, that explains the running lean but not the knock. Also discovered my turbo is shot to hell and needs to be replaced. Cause is pending, but we're betting on oil return line issues I had a few months back. Line is going to be rerun to the girdle. Due to time constraints, I'm replacing the 5857 with a BB 6262.
Christmas should be fun this year.
The lean reading on the wideband was due to a loose wastegate. The metallic sound I was hearing? Exhaust leak. Looks like one of the bolts broke off in the manifold. I'm lucky I didn't lose the WG altogether.
So, that explains the running lean but not the knock. Also discovered my turbo is shot to hell and needs to be replaced. Cause is pending, but we're betting on oil return line issues I had a few months back. Line is going to be rerun to the girdle. Due to time constraints, I'm replacing the 5857 with a BB 6262.
Christmas should be fun this year.
Thread Starter
Joined: Sep 2004
Posts: 4,894
Likes: 9
From: Tampa, FL
Bunch of little problems creating a bigger one. But I can sleep easy knowing the car is now in good hands and not sitting in my garage broke anymore. It'll feel that much better once I get it back.
