TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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Recently it’s taken a lot longer for the car to start up. I used to just turn the key and it would fire up immediately, now I have to keep the key turned for a good 2-3 seconds. Once it started up it runs rough for a couple seconds and it smells like gas. Also when it's warmed up and I coast around 60-70mph it backfires a couple times. Then I took a buddy to the airport (about a 1.5hr drive) and when I put it in park it died. When I'd start it up again it shook and wouldn't go faster than 5mph. I replaced the fuel injectors last year with new Bosch 22#, and it has a brand new distributor cap and rotor. The spark plugs are only 1 year old as well. I tested the fuel pressure and that is normal. Then I replaced the ignition module to see if that would help. That seemed to fix the problem for one day, now the problem is back again. I'm thinking it has something to do with the O2 sensor or the fuel/air mixture, but I'm not getting an engine light. Help!
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
I replaced the O2 sensor today and there was no change in the problem. I've noticed that on a cold start, the car fires up perfectly without any issues. But when it's warmed up and I let it sit and hour or so, it stumbles and smells extremely rich when I turn it on.
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
You need a scanner to see what the sensor readings are. I'd guess your temp sensor may have failed and the ECM always thinks the engine is always cold.
Re: I need some help with a series of weird problems
I haven't been able to run a scanner yet but I did replace the coolant temperature sensor and the problem is still there. How would I test the vacuum system?
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
Just looked for codes with the paper clip method and nothing came up, just the Code 12 diagnostic one. I started it up after clearing the ECM just for kick and it reeks of gasoline. So I'm thinking that maybe there's something that keeps spraying gas into the cylinders right after the car is shut off... but I don't know I' running out of ideas. Leaking injectors? but I just put in brand new 22# injectors 6 months ago.
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
I replaced all of the vacuum lines (there was a hole in one of the lines) and the MAP sensor....but the problem still exists. I've noticed that if I start it up immediately after shutting it down it starts without a problem. It only hesitates and smells like gas if I let it sit for more than 5min or so.
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
Quote:
Originally Posted by oifish
I replaced all of the vacuum lines (there was a hole in one of the lines) and the MAP sensor....but the problem still exists. I've noticed that if I start it up immediately after shutting it down it starts without a problem. It only hesitates and smells like gas if I let it sit for more than 5min or so.
That's usually a sign that an injector is leaking (flooding the engine). You may need to put a fuel pressure gauge on it and see it it falls quickly when you turn the key off.
Re: I need some help with a series of weird problems
Quote:
Originally Posted by jv9999
That's usually a sign that an injector is leaking (flooding the engine). You may need to put a fuel pressure gauge on it and see it it falls quickly when you turn the key off.
Checked the pressure today and it dropped quickly after I shut the car off. Is there an easier way to remove the injectors because I have bosch instead of the stock ones. I thought I saw somewhere there was a way but I can't remember where or who I heard it from.
Re: I need some help with a series of weird problems
Quote:
Originally Posted by oifish
Checked the pressure today and it dropped quickly after I shut the car off. Is there an easier way to remove the injectors because I have bosch instead of the stock ones. I thought I saw somewhere there was a way but I can't remember where or who I heard it from.
It doesn't matter. You'll need to remove the upper plenum and fuel rail. Get new upper intake gaskets before you start.
Re: I need some help with a series of weird problems
Is there any problem with leaving seafoam in the gas tank for a week or so? I added some to the tank just to see if dirty injectors were the culprit. I have to go back up to school tonight and the car will sit for a week while I wait for the injectors.
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
Jon called from FIC and he said the injectors were fine. We came to the conclusion that the FPR must be bad. When I took the injectors out there was gas in the plenum. He said usually a bad FPR is the cause of that. With the plenum off I'm replacing the FPR and the EGR as well. The old FPR had some tears around the center of the diaphragm...so I'm hoping I've finally found the cause of these problems.
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System
Re: I need some help with a series of weird problems
Quote:
Originally Posted by oifish
Jon called from FIC and he said the injectors were fine. We came to the conclusion that the FPR must be bad. When I took the injectors out there was gas in the plenum. He said usually a bad FPR is the cause of that. With the plenum off I'm replacing the FPR and the EGR as well. The old FPR had some tears around the center of the diaphragm...so I'm hoping I've finally found the cause of these problems.
yea if you have fuel in the plenum it can't come from injectors.. They are way below the plenum.. the fuel can come from 2 places to the plenum, a bad FPR or the evac system is sucking fuel through the cannister, not likely.. i would put my money on the FPR. good luck
Re: I need some help with a series of weird problems
Yea I would say fuel pressure regulator diaphram/ FPR unit. That little rubber diaphram is as thin as a gum wrapper, but made of fuel resistant rubber. They can burst over time if it's the original. Fuel cant get to the plenum any other way. Replace that sumbich.!
Re: I need some help with a series of weird problems
FIXED! With the new FPR diaphragm in all the problems are gone. With all the new sensors and vacuum lines too it runs like a dream. Thanks all for your help!
__________________ Mods: K&N, 1-5/8" Hedman Headers, Hi-Flow Cat, Hooker Super Competition 3" Cat-Back Exhaust System