1998 Chevy Monte Carlo EGR problem?

Tiny
KRUQNUT
  • 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"

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Saturday, September 12th, 2009 AT 9:21 PM

38 Replies

Tiny
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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

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Sunday, September 13th, 2009 AT 8:06 AM
Tiny
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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.

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Sunday, September 13th, 2009 AT 8:21 AM
Tiny
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Our video collection should help in showing you how some things can be checked

http://www.2carpros.com/car_repair_video/how_to_scan_your_car.htm

http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm

http://www.2carpros.com/car_repair_video/test_engine_ignition_system.htm

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Sunday, September 13th, 2009 AT 8:32 AM
Tiny
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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.

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Sunday, September 13th, 2009 AT 9:49 AM
Tiny
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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

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Sunday, September 13th, 2009 AT 9:33 PM
Tiny
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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

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Monday, September 14th, 2009 AT 6:01 AM
Tiny
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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.

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Monday, September 14th, 2009 AT 9:39 AM
Tiny
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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.

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Monday, September 14th, 2009 AT 9:44 AM
Tiny
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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.

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Monday, September 14th, 2009 AT 4:15 PM
Tiny
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What about the fuel pressure?

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Tuesday, September 15th, 2009 AT 6:11 AM
Tiny
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The fuel pressure was ok. It was within spec I believe, 40 psi with the car off, 47 psi when pump was priming, dropped a bit when engine idled, drops maybe 1-2 psi more when its under load, stays pretty consistent when misfiring but flucuates maybe 1-2 psi.

I read that good fuel pressure doesn't always mean it has enough flow. If I press the gas in hard it misfires immediately as opposed to if I push it gradual it will climb to 3k rpms, I cleaned the MAF and now I get abotu 500 more rpm out of it.

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Tuesday, September 15th, 2009 AT 7:40 AM
Tiny
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I finally got the fuel filter off, the old one was pretty grimy, thick black crap poored out of it then it went completely clogged, I put a new filter on but same symptoms.

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Tuesday, September 15th, 2009 AT 11:20 AM
Tiny
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I pulled a p1676 code off an OBDII scanner, any idea what this is?

I read somewhere someone mention about the brake booster, could my problems be from vacuum failure in teh brake booster? I noticed when I first started the car that my ABS would kick in when I hit the brakes coming to the end of my driveway at like 5 mph.

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Tuesday, September 15th, 2009 AT 4:32 PM
Tiny
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I jotted down some values from the freeze data, the car wasn't running when it threw the code, at least it said 0 rpms,

MAP sensor at 99 KPA

Short term fuel trim 1 0.8%
Long term fuel trim 1 0.8%
Short term fuel trim 3 -96.7% (is that normal?)
Long term fuel trim 3 8.5%

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Tuesday, September 15th, 2009 AT 4:35 PM
Tiny
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DTC P1676 - EVAP PURGE VALVE CONTROL CIRCUIT

The Output Driver Module (ODM) is used by the PCM to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding on. ODM have the capability of diagnosing each output circuit individually.
Conditions required to set DTC are:
Ignition is on. " Improper voltage level detected on output circuit controlling EVAP purge solenoid valve. " Conditions present for at least 30 seconds. "
Diagnostic Procedures
Circuit Description

Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK, then go to next step. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, check voltage between ground and EVAP purge valve control circuit at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6). Set ammeter to 10-amp range. Check current between ground and EVAP purge valve control circuit at PCM connector. Monitor reading for a minimum of 2 minutes. If current is.05-.50 amp, go to step 11). If current is not.05-.50 amp, go to next step. Disconnect EVAP purge valve connector. Using DVOM, check voltage between ground and EVAP purge valve control circuit at harness connector. If voltage reading is zero volts, go to step 10). If voltage reading is not zero volts, go to next step. Locate and repair short to voltage in EVAP purge valve control circuit. After repairs, go to step 16). 5. Turn ignition off. Remove and inspect fuse for EVAP purge valve. If fuse is blown, go to next step. If fuse is okay, go to step 8). Locate and repair short to ground in ignition feed circuit for EVAP purge vent valve. Replace fuse. After repairs, go to step 16). Disconnect EVAP purge valve. Turn ignition on. Check voltage between ground and ignition feed circuit for EVAP purge valve harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13). Check for an open or short to ground in EVAP purge valve control circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to next step. Check EVAP purge valve control circuit and ignition feed circuit for poor terminal connection at EVAP purge valve and at PCM connector. Repair as necessary. After repairs, go to step 16). If connections are okay, go to step 14).

Turn ignition off. Reconnect PCM harness connector. Disconnect EVAP purge valve connector. Turn ignition on. Connect a test light between EVAP purge valve control circuit and ignition feed circuit terminals at EVAP purge valve connector. Using scan tool, select OUTPUTS TEST function and cycle EVAP purge solenoid on and off. If test light flashes on and off, see DIAGNOSTIC AIDS. If test light does not flash, go to next step. Check EVAP purge valve control circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 15). Locate and repair open in ignition feed circuit to EVAP purge valve. After repairs, go to step 16). Replace EVAP purge valve. After replacing valve, go to step 16). 14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until this DTC test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

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Tuesday, September 15th, 2009 AT 4:53 PM
Tiny
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It isn't really clear what each step is in that description.
I can't figure out what step 6 is, etc.

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Tuesday, September 15th, 2009 AT 8:12 PM
Tiny
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TESTS W/CODES - 3.1L -1998 Chevrolet Monte Carlo

NOTE: For circuit reference, see WIRING DIAGRAMS - 3.1L article.
DTC P1676 - EVAP PURGE VALVE CONTROL CIRCUIT

Circuit Description
The Output Driver Module (ODM) is used by the PCM to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding on. ODM have the capability of diagnosing each output circuit individually.
Conditions required to set DTC are:
Ignition is on. " Improper voltage level detected on output circuit controlling EVAP purge solenoid valve. " Conditions present for at least 30 seconds. "

Diagnostic Procedures

1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK, then go to next step.

2. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using DVOM, check voltage between ground and EVAP purge valve control circuit at PCM connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6).

3. Set ammeter to 10-amp range. Check current between ground and EVAP purge valve control circuit at PCM connector. Monitor reading for a minimum of 2 minutes. If current is.05-.50 amp, go to step 11). If current is not.05-.50 amp, go to next step.

4. Disconnect EVAP purge valve connector. Using DVOM, check voltage between ground and EVAP purge valve control circuit at harness connector. If voltage reading is zero volts, go to step 10). If voltage reading is not zero volts, go to next step.

5. Locate and repair short to voltage in EVAP purge valve control circuit. After repairs, go to step 16).

6. Turn ignition off. Remove and inspect fuse for EVAP purge valve. If fuse is blown, go to next step. If fuse is okay, go to step 8).

7. Locate and repair short to ground in ignition feed circuit for EVAP purge vent valve. Replace fuse. After repairs, go to step 16).

8. Disconnect EVAP purge valve. Turn ignition on. Check voltage between ground and ignition feed circuit for EVAP purge valve harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 13).

9. Check for an open or short to ground in EVAP purge valve control circuit. Repair as necessary. After repairs, go to step 16). If circuit is okay, go to next step.

10. Check EVAP purge valve control circuit and ignition feed circuit for poor terminal connection at EVAP purge valve and at PCM connector. Repair as necessary. After repairs, go to step 16). If connections are okay, go to step 14).

11. Turn ignition off. Reconnect PCM harness connector. Disconnect EVAP purge valve connector. Turn ignition on. Connect a test light between EVAP purge valve control circuit and ignition feed circuit terminals at EVAP purge valve connector. Using scan tool, select OUTPUTS TEST function and cycle EVAP purge solenoid on and off. If test light flashes on and off. If test light does not flash, go to next step.

12. Check EVAP purge valve control circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to step 15).

13. Locate and repair open in ignition feed circuit to EVAP purge valve. After repairs, go to step 16).

14. Replace EVAP purge valve. After replacing valve, go to step 16).

15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Turn ignition on, with engine off.

16. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Monitor SPECIFIC DTC info for this DTC until this DTC test runs. If scan tool indicates FAILED THIS IGN, repeat step 2). If scan tool does not indicate FAILED THIS IGN, repair is complete.

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Wednesday, September 16th, 2009 AT 6:21 AM
Tiny
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I just replaced the spark plugs and wires as my plugs were old.

I took it out on the road to try to get a code to throw. I noticed if I tried flooring it it would miss immediately, if I drive like normal it goes fine unless I get to 3k RPM then it starts misfiring.

I noticed in O/D that it starts to miss alot aooner, like 2k rpm, and it misses alot harder, like the car jerks.

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Wednesday, September 16th, 2009 AT 3:15 PM
Tiny
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When testing the MAF with a DVOM what exactly am I checking for? There are 3 wires to my MAF, a yellow one on the left, a black one witha white strip in the middle, and a red one on the right. Which one do I want to check? I tried myself and one of the wires read 4.53V at idle, and dropped down steadily to 4.0V when I increased teh throttle to about 2500 RPM. I didn't test the black wire witha white line in it, the other wire read 14V so im guessing that was the power feed.

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Wednesday, September 16th, 2009 AT 6:30 PM
Tiny
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Ok so I just figured out my s-10 has the same MAF sensor, So I took the sensor off my s-10, cleaned it, and put it on my monte carlo. I started it up, the injectors were pretty loud, but they usually are when I first crank it. Then I ran a bit, it misfired alittle but then it started making it to 4k rpm, and the rev limiter, So I took it on the road and punched it, it worked fine, I drove down the road with the occasional hiccup but it climbed to 6k RPM then cruised at 8- mph fine. I turned around to come back, and punched it again, and then it started missing again and I'm right back where I started. I don't know if it was working good because the engine was really cold or what, It threw no dcodes and now I'm back to where I started, I'm so confused and disapointed with the false hope I was given.

Any ideas?

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Thursday, September 17th, 2009 AT 7:54 AM

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