step on gas, rpms drop 400, rpms shoot up, code 34
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Joined: Jan 2001
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From: Boothwyn, PA, US
step on gas, rpms drop 400, rpms shoot up, code 34
I asked questions a few days ago about serious problems while accelerating. Idle lopes a lot when cold but once it's warm...it is fine, cruise is fine. It's only when I try to accelerate that it has a problem. At low RPMs it has no power at all. If I'm trying to accelrate from low RPMs, I have to get them over 3000 or it just bucks and kicks and what not. Over 300 RPMs under a load, it accelerates but you can hear it missing through the exhaust.
When just sitting there, in neutral, reving the engine, it hesitates. Actually hesitates is too soft a word. When you put you foot on the gas, the tach drop about 400 RPMs then is shoots up like it should. It does this no matter how lightly or slowly you press on the accelerator. In fact.... if you touch is lightly enough, you can make the RPMs drop, and hold there for a couple seconds before it starts back up. Sounds like the TPS to me but it's throughing a Code 34. Its an '85 V6 MPFI so the book says MAF.
I am going to be doing a complete tune up this week so any advice beyond that would be appreciated. I have a feeling that a tune-up won't solve this. The next step after the tune-up is a timing chain.
I'm planning on driving this car 1000 miles from Philly to St. Louis this Saturday so this is going to be an interesting week.
Terry
When just sitting there, in neutral, reving the engine, it hesitates. Actually hesitates is too soft a word. When you put you foot on the gas, the tach drop about 400 RPMs then is shoots up like it should. It does this no matter how lightly or slowly you press on the accelerator. In fact.... if you touch is lightly enough, you can make the RPMs drop, and hold there for a couple seconds before it starts back up. Sounds like the TPS to me but it's throughing a Code 34. Its an '85 V6 MPFI so the book says MAF.
I am going to be doing a complete tune up this week so any advice beyond that would be appreciated. I have a feeling that a tune-up won't solve this. The next step after the tune-up is a timing chain.
I'm planning on driving this car 1000 miles from Philly to St. Louis this Saturday so this is going to be an interesting week.
Terry
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And how's your fuel pressure?
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Thread Starter
Junior Member
Joined: Jan 2001
Posts: 10
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From: Boothwyn, PA, US
I haven't checked the fuel pressure yet. I only have time to work on it each evening for a couple hours before it gets dark.
Monday, I pulled the dash and replaced all the light bulbs and replaced the ECM with an ADS Superchip. I also changed out the Radio and removed some other trim pieces that were broken. The check engine light was burned out so I had to replace it to check the errors. It ran much better over 3000 rpms with the new chip.
Last night, I replaced the Air Filter, Distributor Cap, Rotor, and PCV Valve. It ran much better at all RPMs after this but it still has little power at low RPMs. At or below 2000 rpms, it bogs down really bad and kicks/bucks until the RPMs above 2500. Then it still misses for the next 500 RPMs then runs good above 3000.
Tonight, I'm changing the Plugs and Plug Wires, hand cleaning the Throttle Body, and Replacing all the Belts and Vacuum Hoses. Several of the vacuum hoses are cracked and one is obviously collapsed.
Thursday, I'm replaceing the Fuel Filter, O2 Sensor, and checking the various other components (EGR, TPS, IAC, etc.)
Friday, I'll be swapping out the old vinal seats for a regular set From a '94, and prepareing for the trip back to St. Louis.
To test the fuel pressure, I have to take the intake manifold off right? I'll do that after I get it to St. Louis and can get it in a garage. I plan to check the Cylinder compression and replace the Timing Chain so I'll add a Fuel Pressure Test to the list while I'm at it.
Monday, I pulled the dash and replaced all the light bulbs and replaced the ECM with an ADS Superchip. I also changed out the Radio and removed some other trim pieces that were broken. The check engine light was burned out so I had to replace it to check the errors. It ran much better over 3000 rpms with the new chip.
Last night, I replaced the Air Filter, Distributor Cap, Rotor, and PCV Valve. It ran much better at all RPMs after this but it still has little power at low RPMs. At or below 2000 rpms, it bogs down really bad and kicks/bucks until the RPMs above 2500. Then it still misses for the next 500 RPMs then runs good above 3000.
Tonight, I'm changing the Plugs and Plug Wires, hand cleaning the Throttle Body, and Replacing all the Belts and Vacuum Hoses. Several of the vacuum hoses are cracked and one is obviously collapsed.
Thursday, I'm replaceing the Fuel Filter, O2 Sensor, and checking the various other components (EGR, TPS, IAC, etc.)
Friday, I'll be swapping out the old vinal seats for a regular set From a '94, and prepareing for the trip back to St. Louis.
To test the fuel pressure, I have to take the intake manifold off right? I'll do that after I get it to St. Louis and can get it in a garage. I plan to check the Cylinder compression and replace the Timing Chain so I'll add a Fuel Pressure Test to the list while I'm at it.
Thread Starter
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Joined: Jan 2001
Posts: 10
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From: Boothwyn, PA, US
**UPDATE**
Okay, I've got a minor problem. I went to clean out the intake by spraying Injector Approved cleaner in through the throttle body. When I twisted open the throttle, I saw what can only be described as "SLUDGE" coating the entire insde of the intake plenum and the back side of the throttle body. I pulled the throttle body and it took me 45 minutes of scrubbing with a tooth brush to get it off. The intake plenum is still coated. I'm not going to have time to pull it before I drive back to St. Louis but I sprayed the inside real good. The big problem is that the runner opeings inside the plenum that lead to the cylinders have deposites built up all around them. They are only open about the size of a dime. I know I have to pull the plenum and clean them out but what I'm wondering is what can cause this?
I understand that it's going to get dirty in there but this SLUDGE was so thick I used an entire can of cleaner and a tooth brush just to get it off the back side of the throttle body. It would not have come off without the tooth brush... It was too thick.
By the way, the plugs looked fine but were oily on the threads...I replaced them anyway. Plug wires were okay too....but but there was oil on the outside of the rubber on the plug ends. I replaced them with Accel 8mm wires. The upper radiator hose was fine yesterday while it was running but had collapsed over night. I'm told that its probably the radiator cap or overflow tube is clogged. I had to cut it off because the clamp was rusted and wouldn't budge.
Tonight I have to re-connect the throttle body to the intake plenum, put on a new upper radiator hose, replace the radiator cap, check the return hose, and re-set the TPS. I took it loose from the throttle body before I cleaned it so it wouldn't be damaged. I couldn't get the IAC off because I didn't have a big enough wrench.
Terry
Okay, I've got a minor problem. I went to clean out the intake by spraying Injector Approved cleaner in through the throttle body. When I twisted open the throttle, I saw what can only be described as "SLUDGE" coating the entire insde of the intake plenum and the back side of the throttle body. I pulled the throttle body and it took me 45 minutes of scrubbing with a tooth brush to get it off. The intake plenum is still coated. I'm not going to have time to pull it before I drive back to St. Louis but I sprayed the inside real good. The big problem is that the runner opeings inside the plenum that lead to the cylinders have deposites built up all around them. They are only open about the size of a dime. I know I have to pull the plenum and clean them out but what I'm wondering is what can cause this?
I understand that it's going to get dirty in there but this SLUDGE was so thick I used an entire can of cleaner and a tooth brush just to get it off the back side of the throttle body. It would not have come off without the tooth brush... It was too thick.
By the way, the plugs looked fine but were oily on the threads...I replaced them anyway. Plug wires were okay too....but but there was oil on the outside of the rubber on the plug ends. I replaced them with Accel 8mm wires. The upper radiator hose was fine yesterday while it was running but had collapsed over night. I'm told that its probably the radiator cap or overflow tube is clogged. I had to cut it off because the clamp was rusted and wouldn't budge.
Tonight I have to re-connect the throttle body to the intake plenum, put on a new upper radiator hose, replace the radiator cap, check the return hose, and re-set the TPS. I took it loose from the throttle body before I cleaned it so it wouldn't be damaged. I couldn't get the IAC off because I didn't have a big enough wrench.
Terry
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