SES codes jumping
#22
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Today the mechanic checked my fuel pressure in was in the range of 45 when reved it went to 35..they changed the fuel filter and checked the egr valve he also pulled the wires of the coils while car running to see how the spark was.. he also did the test with carb cleaner for vac leaks and sprayed my wires with water.. everything turned out good . I told him i put chevron fuel treatment so he told me to run it for the rest of the week to see if it clears..if not he will clean my injectors with some unit he has there.I was thinking should i change my wires anyway even though there was no sign of spark?
#23
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#24
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I was going through forums here and found someone else who had the same problem ..
His qoute:
"EUREKA!!!! Found the problem. I have checked this numerous times but nothing. It is the UIM. There is pooling under the sc. I wonder if the seafoam yesterday cleaned it out enough to let it pool. I dunno but there is now."
Don,, End qoute
I'm assumming UIM is the upper intake manifold..Is it possible a gasket leak can cause a misfire on hi boost?
His qoute:
"EUREKA!!!! Found the problem. I have checked this numerous times but nothing. It is the UIM. There is pooling under the sc. I wonder if the seafoam yesterday cleaned it out enough to let it pool. I dunno but there is now."
Don,, End qoute
I'm assumming UIM is the upper intake manifold..Is it possible a gasket leak can cause a misfire on hi boost?
#25
DINOSAURUS BOOSTUS
Expert Gearhead
Found the problem. well actually a couple problems. Your mechanic is going off "should be" and not the specification which is 48-52 at idle and when you blip a boosted car you should see 60-70psi, not a drop off. When the pressure went down, that should have been a clear indicator that the pump is not keeping up with demand.
Add another problem actually. Coolant or oil pooling on the LIM does not cause a multiple misfire. At most a bad LIM gasket may cause one or two cylinders to misfire, but this is extremely uncommon. Usually you never know your LIM is bad until you pull it. Pooling on top is a simple leak, not something that is getting into the cylinders. When we think about what is going on with a motor, it is important to think about how things work and if A equals B or if C is involved.
Problem 1: Mechanic
Problem 2: Fuel pump
Problem 3: Misdiagnosis
Add another problem actually. Coolant or oil pooling on the LIM does not cause a multiple misfire. At most a bad LIM gasket may cause one or two cylinders to misfire, but this is extremely uncommon. Usually you never know your LIM is bad until you pull it. Pooling on top is a simple leak, not something that is getting into the cylinders. When we think about what is going on with a motor, it is important to think about how things work and if A equals B or if C is involved.
Problem 1: Mechanic
Problem 2: Fuel pump
Problem 3: Misdiagnosis
#26
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The lack of fuel pressure is causing a lean condition. I'm will to bet if you scan the LTFT you will see those numbers way high. You may also see a lot of knock.
#27
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Hey Dan,
Thanks for the info, on the fuel pressure.. it was the mechanics worker that tested it and game those figures.. as i sat in the car he told me to put it in drive and step on the brakes and gas i asked him what it did and he told me it went to 35..so do i have to change my fuel pump?
the uim problem is not mine i was qouting some one else who had the same promblem and posted it here..sorry for the confusion/misunderstanding.
Thanks for the info, on the fuel pressure.. it was the mechanics worker that tested it and game those figures.. as i sat in the car he told me to put it in drive and step on the brakes and gas i asked him what it did and he told me it went to 35..so do i have to change my fuel pump?
the uim problem is not mine i was qouting some one else who had the same promblem and posted it here..sorry for the confusion/misunderstanding.
#28
DINOSAURUS BOOSTUS
Expert Gearhead
Were the readings done before or after the fuel filter was changed? it is possible that the filter was clogged and the flow making it through the filter was not sufficient to maintain the pressure. Although the chances of that being the case are slim.
I would say, yes change the fuel pump. Those readings of it going down to 35psi shouldn't have been possible if the pump was good.
I would say, yes change the fuel pump. Those readings of it going down to 35psi shouldn't have been possible if the pump was good.
#29
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Were the readings done before or after the fuel filter was changed? it is possible that the filter was clogged and the flow making it through the filter was not sufficient to maintain the pressure. Although the chances of that being the case are slim.
I would say, yes change the fuel pump. Those readings of it going down to 35psi shouldn't have been possible if the pump was good.
I would say, yes change the fuel pump. Those readings of it going down to 35psi shouldn't have been possible if the pump was good.
#30
DINOSAURUS BOOSTUS
Expert Gearhead
Most likely it'* the pump. If the car is still exhibiting the same behavior/issues, I'd go straight to changing the pump. The problem should have corrected itself if the filter was the issue.