T0 much fuel? Please help.. Going nuts soon. (Kinda long)
06-03-2009, 12:29 PM
#1
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T0 much fuel? Please help.. Going nuts soon. (Kinda long)
Car is a 944 turbon -89
Related mods
Maf-kit (Bosch H5M5 no piggyback)
3.0 bars fuelpressure (98 octane fuel)
Reworked head (Larger valves 48mm)
CR 9:1
Milledgecam... supposed to idle smoothly
Symptoms (Cold start): So i start the car it runs for about 10-15 sec just fine. Smoothest idle ever. Then it starts to missfire and backfire badly. If i use the throttle i can keep it runing for as long as i wish. If i let go it idles for about 5 sec around 700 rpm missfiring as it goes then just dies. After this its hard or impossible to start the car again for aboud an hour. Then the whole thing starts all over again.
So im thinking the car is getting alot more fuel then it should. I had problems with the car running badly on idle before. Then i fixed a major leak in my vacuum system. And now it's a total disaster. I took a pressure test on the cylinders (Engine cold)
Cylinder pressure
1 9.9 kg/cm2
2 9.1 kg/cm2
3 9,3 kg/cm2
4 9.5 kg/cm2
Checked the hose between the BTR and intake. No fuel there. Tried with and without O2 sesor There's no vacuumleaks (Tried it with pressureised air). No exhaustleaks.
The injectors are not the original ones, they are 350cc (33 lb/h). I have a MAF system with 2 different setups (No pigyback). 788cc (83 lb/h) with e85 as fuel. The mode im runing now is standard 98 ocatane pumpfuel with "Original" injectors. Can't seem to get a hold on the guy that programed the chip. It's usualy not a problem so i guess he's just been away from the computer. So i guess it's still possible that the injectors are to large but i doubt it.
Haven't checked fuelpressure yet.
Related mods
Maf-kit (Bosch H5M5 no piggyback)
3.0 bars fuelpressure (98 octane fuel)
Reworked head (Larger valves 48mm)
CR 9:1
Milledgecam... supposed to idle smoothly
Symptoms (Cold start): So i start the car it runs for about 10-15 sec just fine. Smoothest idle ever. Then it starts to missfire and backfire badly. If i use the throttle i can keep it runing for as long as i wish. If i let go it idles for about 5 sec around 700 rpm missfiring as it goes then just dies. After this its hard or impossible to start the car again for aboud an hour. Then the whole thing starts all over again.
So im thinking the car is getting alot more fuel then it should. I had problems with the car running badly on idle before. Then i fixed a major leak in my vacuum system. And now it's a total disaster. I took a pressure test on the cylinders (Engine cold)
Cylinder pressure
1 9.9 kg/cm2
2 9.1 kg/cm2
3 9,3 kg/cm2
4 9.5 kg/cm2
Checked the hose between the BTR and intake. No fuel there. Tried with and without O2 sesor There's no vacuumleaks (Tried it with pressureised air). No exhaustleaks.
The injectors are not the original ones, they are 350cc (33 lb/h). I have a MAF system with 2 different setups (No pigyback). 788cc (83 lb/h) with e85 as fuel. The mode im runing now is standard 98 ocatane pumpfuel with "Original" injectors. Can't seem to get a hold on the guy that programed the chip. It's usualy not a problem so i guess he's just been away from the computer. So i guess it's still possible that the injectors are to large but i doubt it.
Haven't checked fuelpressure yet.
06-03-2009, 12:32 PM
#2
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make sure that the spark pluggs are actually firing. I had a problem with my reffrence sensor and it wasnt reading the where TDC was all the time. Ended up making the engine missfire sometimes but not all the time. Wierd problem.
06-03-2009, 01:13 PM
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well this one runs good for about 10 sec as i said. so the plugs cant be the problem. I guess the reference sensors could be the problem. Will check that...
06-03-2009, 09:51 PM
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Changed sparkplugs now it runs better. Still has bad idle... Now im thinking it could be the rest of my ignitionparts.... Om gonna clean up the coil rotor and distributor cap tomorow...
06-04-2009, 07:06 AM
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I have just changed to much... Intake on the turbo is to large to name one problem... Since it's a garret, the stock turbo wont fit the car anymore... so rebuilding to orirginal is just not giong to work... But i dont think the MAF is the problem...
