Mechanics

CHEVY EGR PROBLEM?

1998 Chevrolet Monte Carlo

Engine Mechanical problem
1998 Chevy Monte Carlo 6 cyl Front Wheel Drive Automatic 168000 miles

I have a 1998 monte carlo Ibought about a month ago, When I got it a code quickly came up and I had it scanned and reset, It read EGR flow insufficient. It came up again. The only problems I felt in the engine was a very occasionaly msifire while idling once the car was warmed up, sometimes a slightly rough idle while at a stop. THis rough idle would go away if I put it into park then into gear.

Well a couple days ago I was coming home on the highway, and all the sudden my tach started jumping all over the place so I turned down my music and I heard it misfiring. I dropped my RPMS and rode the rest of the way home with an occasional misfire that would almost stall the engine.

When I got home the car stalled out when I put it into park and got out to open the hood. It wouldn't stay running at all, the idling was incosistent and it would miss and stall out. If I gave it gas, once it approached 2500 RPMS it would misfire very heavily and not go over 2500 RPMS at all.

THe next day I started the car and it idled fine and smooth, but if I gave it gas it would start missing at 2500 rpms, I can run it at 2000 rpms fine with no missing.

I took the egr valve off and put some carb cleaner in the tube and started the car up
the one side of the EGR valve that goes into the intake is sucking in air pretty well, whereas the other side is pushing out air.

I'm not sure where to go with this problem now as i've never experienced anything like it.

I have the 3.1L v6 engine " M"
Avatar
Kruqnut
September 12, 2009.



Check engine light on and flashing?
I would suspect a tune up and or bad coil check for DTC s codes
check if have spark on each and every cylinder check at the coil side
check fuel pressure

BMRFIXIT
Sep 13, 2009.
Its not flashing, it was on constant, I just reset it by unplugging the computer for 10 minutes. Now theres no code for anything in thaere, the car starts and idle, but still I can't rev it over 2500 RPM, it just sputters like nuts. I can hold it at 1800 RPM no problem without a single misfire.

How would I go about checking the fuel pressure? I have a compression tester I borrowed from autozone.

I would think it was a spark problem, but it idles fine just misfired on ALL cylinders if I try to bring the RPMS up. Even when I press the gas to bring the rpms up and it sputters hard, no codes get stored.

I'm kinda new to working on the internals of a car's engine so more specific help would be nice, like how to go through checking these things out.

Thank you.

Tiny
Kruqnut
Sep 13, 2009.
Ok I found the fuel pressure testing port and used a fuel pressure tester to check the pressure.

It was at spec, 40 or close, the test kit says 41-47PSI is my spec. It was at 40 even when key off, jumped to 45-46 when priming, then dropped back to 40. With the engine running it dropped to about 35-37 psi with the fuel regulator vacuum in effect, if I removed the hose from the fuel regulator it would jump to 48 PSI.

If I leave the test gauge connected after about 2 hours the pressure dropped down to 10psi, but immediatly jumped to 46 psi when I turned the key to activate the pump again.

I thought everything seemed good tho the values displayed were about 1psi under spec.

When I pull the throttle slightly it drops alittle pressure, and is about the same pressure when at 2k rpm as when it starts misfiring at 2500 rpm, tho the pressure flucuates about 1-2 psi less when it was under load.

Does any of this indicate a fuel problem? One that would cause my engine to completely misfire over 2500 rpms?

It still idles perfect while cold, I'm stumped on where to check next.

No engine codes even tho it misfires and almost dies when I try to get it above 2500 rpms.

Tiny
Kruqnut
Sep 13, 2009.
I remember the first time I had it scanned something showed up about a Fuel Evaporation Canister error of some sort, Could this be something that is causing this problem? I just read a post somewhere about an Isuzu rodeo that wouldn't rev over 4k rpm, would just misfire. Someone suggested the evaporation canister solenoid. Could this be my issue?

Or could it possibly be the catalytic converter catastrophically failed on me?

Still strange I get no codes

Tiny
Kruqnut
Sep 13, 2009.
Evap system will not cause a misfiring
if have check engine light on you should have a code s
it could be a lot of things have to start with the basic check

fuel pressure, spark on all cylinders, codes
compression and timing

BMRFIXIT
Sep 14, 2009.
I don't have a check engine light on, I cleared it the other day hoping that the computer just needed to be reset after I cleaned the EGR system out.
I unplugged teh battery cable for 15 minutes then plugged it back in. No new codes have been stored.

My fuel pressure is ok I think, I described the reading I got.

I'm getting spark on all cylinders because it idles smoothly.

I don't know how to check my timing or compression.

Tiny
Kruqnut
Sep 14, 2009.
Could my timing be off? That wouldn't effect my idle or lower rpm running ability?

It purrs like a kitten up to 2500 RPM then it misfires constantly and won't go higher.

Fuel pressure checks out and no codes are storing, tell me where to go next.

Tiny
Kruqnut
Sep 14, 2009.
I took the ICM and ignition coils into autozone to have them tested, I got 0 resistance on tests on all 3 coils, and the ICM passed their test.

Tiny
Kruqnut
Sep 14, 2009.
What about the fuel pressure?

BMRFIXIT
Sep 15, 2009.
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