need help 944 won't idle
01-09-2005, 02:46 PM
#1
Track Day
Thread Starter
Join Date: Jun 2004
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
need help 944 won't idle
Hey folks! I have a little problem here, I’m wondering if you could help me out? The combined knowledge and experience of this forum never ceases to amaze me!
Here’s the story. I’m providing a lot of details as they may be relevant to someone out there. I apologize for the excess, just trying to be thorough and felt that too much info is better than not enough. For those who want to cut to the chase, skip ahead to the last paragraph.
My car is an 85.5 944 N/A. The maintenance had been procrastinated a bit here and there until last summer. My “to do” list included replacing the cam belt, balancing shaft belt, the 4 applicable rollers, front-end seals. I also pulled the head for a valve job and replace the valve guides (and stem seals). Also replaced fuel filter, air filter, oil filter, dist cap, rotor, thermostat, thermo switch, all applicable gaskets and had some welding done on my exhaust manifold. While in there I inspected the cylinder walls and cleaned up the piston heads. Took a bunch of photos of most of the process, which I’ll send to Clark’s Garage (and anyone else who may be interested) in case he wants to use them.
About a month before the project, my car developed some vibrations and I posted a prompt here and received suggestions relating to the balance shaft belt.
One day about a week before the project started the started running real bad. I was only a couple of blocks from home so I managed to limp back to the nest but it was bad. It ran very rough and felt like a misfire. The car wouldn’t idle, would stall unless I kept the RPM’s up…again reminiscent of a misfire. I’ve been driving this car for 10 years now and been through my share of troubles/repairs etc but I can’t really recall this car ever misfiring for any reason. I’ve experience plenty of misfires on other engines though. I suspected that the neglected maintenance on the ignition system was a likely culprit so I decided to park the car and begin the project as planned. If the problem returned I would be able to rule out a bunch of newly replaced parts all at once.
When I opened the belt covers I did in fact find that my balance shaft belt had snapped and was wedged around the lower balance shaft gear. First mystery solved. I removed the belts, pulled the head, had the valve job done when there was a hiatus of 4 months due to some professional obligations. I got back to work on the car recently and managed to get puzzle back together without any extra pieces. Today I started the engine for the first time. It ran rough for a few seconds then began to smooth out. I realized that the prolonged sit probably wasn’t the best for the engine but I did remember to add a little oil to the cylinders before the first fire up and made sure the oil level was up to par before the first start. The cam and lifters tapped for a few seconds then the oil reached them and they were happy. I stopped the engine, checked and added a little more oil to the pan then fired it up again. After a few moments the engine was running smooth and ….well….I don’t really know how to describe it other than it felt light and very responsive. Not dogged and tired like it did before the project.
THE PROBLEM: It wouldn’t idle. When I release the gas pedal, it just dies. Doesn’t sputter, just cuts out. Now when I reconnected the throttle cable, I noticed that it had slack. I paused in confusion, as I don’t ever recall the cable having any slack in it. I played around with it a bit but it seemed to be connected securely. I may have screwed up the reinstallation but it doesn’t seem that difficult…I mean after everything else I just did, the throttle cable seemed about as complicated as oiling a bicycle chain! But nevertheless, I’m standing here scratching my head. The car doesn’t idle rough like it’s misfiring, it just seems like the slack in the throttle cable allows the throttle to close all the way and cut off the fuel. I didn’t mess with the screw the stops the throttle lever though. The only thing I did to the throttle body was “wipe off” the oil crud that was obviously sucked into it from my leaky balance shaft seals. I noticed the cable tension adjuster in the firewall, which is backed out almost all of the way, but I have never touched that either. I did notice what appears to be a darker area of throttle cable where it enters the sheathing, which may indicate a change in cable length. So I’m wondering if this situation is in anyway related to what initially appeared to be a misfire last summer? Is slack in the throttle cable going to affect the car’s idle? If so, what could be causing the slack? Is it possible that an idle adjustment is needed in light of the recently replaced parts?
Any ideas?
I'm going to try some things suggested by AFJuvat today.
Here’s the story. I’m providing a lot of details as they may be relevant to someone out there. I apologize for the excess, just trying to be thorough and felt that too much info is better than not enough. For those who want to cut to the chase, skip ahead to the last paragraph.
My car is an 85.5 944 N/A. The maintenance had been procrastinated a bit here and there until last summer. My “to do” list included replacing the cam belt, balancing shaft belt, the 4 applicable rollers, front-end seals. I also pulled the head for a valve job and replace the valve guides (and stem seals). Also replaced fuel filter, air filter, oil filter, dist cap, rotor, thermostat, thermo switch, all applicable gaskets and had some welding done on my exhaust manifold. While in there I inspected the cylinder walls and cleaned up the piston heads. Took a bunch of photos of most of the process, which I’ll send to Clark’s Garage (and anyone else who may be interested) in case he wants to use them.
About a month before the project, my car developed some vibrations and I posted a prompt here and received suggestions relating to the balance shaft belt.
One day about a week before the project started the started running real bad. I was only a couple of blocks from home so I managed to limp back to the nest but it was bad. It ran very rough and felt like a misfire. The car wouldn’t idle, would stall unless I kept the RPM’s up…again reminiscent of a misfire. I’ve been driving this car for 10 years now and been through my share of troubles/repairs etc but I can’t really recall this car ever misfiring for any reason. I’ve experience plenty of misfires on other engines though. I suspected that the neglected maintenance on the ignition system was a likely culprit so I decided to park the car and begin the project as planned. If the problem returned I would be able to rule out a bunch of newly replaced parts all at once.
When I opened the belt covers I did in fact find that my balance shaft belt had snapped and was wedged around the lower balance shaft gear. First mystery solved. I removed the belts, pulled the head, had the valve job done when there was a hiatus of 4 months due to some professional obligations. I got back to work on the car recently and managed to get puzzle back together without any extra pieces. Today I started the engine for the first time. It ran rough for a few seconds then began to smooth out. I realized that the prolonged sit probably wasn’t the best for the engine but I did remember to add a little oil to the cylinders before the first fire up and made sure the oil level was up to par before the first start. The cam and lifters tapped for a few seconds then the oil reached them and they were happy. I stopped the engine, checked and added a little more oil to the pan then fired it up again. After a few moments the engine was running smooth and ….well….I don’t really know how to describe it other than it felt light and very responsive. Not dogged and tired like it did before the project.
THE PROBLEM: It wouldn’t idle. When I release the gas pedal, it just dies. Doesn’t sputter, just cuts out. Now when I reconnected the throttle cable, I noticed that it had slack. I paused in confusion, as I don’t ever recall the cable having any slack in it. I played around with it a bit but it seemed to be connected securely. I may have screwed up the reinstallation but it doesn’t seem that difficult…I mean after everything else I just did, the throttle cable seemed about as complicated as oiling a bicycle chain! But nevertheless, I’m standing here scratching my head. The car doesn’t idle rough like it’s misfiring, it just seems like the slack in the throttle cable allows the throttle to close all the way and cut off the fuel. I didn’t mess with the screw the stops the throttle lever though. The only thing I did to the throttle body was “wipe off” the oil crud that was obviously sucked into it from my leaky balance shaft seals. I noticed the cable tension adjuster in the firewall, which is backed out almost all of the way, but I have never touched that either. I did notice what appears to be a darker area of throttle cable where it enters the sheathing, which may indicate a change in cable length. So I’m wondering if this situation is in anyway related to what initially appeared to be a misfire last summer? Is slack in the throttle cable going to affect the car’s idle? If so, what could be causing the slack? Is it possible that an idle adjustment is needed in light of the recently replaced parts?
Any ideas?
I'm going to try some things suggested by AFJuvat today.
01-09-2005, 04:07 PM
#2
Three Wheelin'
Dangerous:
I suspect that you may be dealing with the throttle body and throttle cabel being out of adjustment, combined with an idle stabilizer problem.
On the later cars like yours, idle is "set" two ways. First is the mechanical adjustment, and second is via the Idle Stabilizer Valve, or ISV.
To set the mechanical idle you need to remove the throttle body and set the mechanical stop. To do this you need to:
1. Loosen the TPS
2. Loosen the 7mm lock nut on the mechanical stop
3. Back out the mechanical stop until it is not touching the throttle plate stop arm
4. Turn the mechanical stop in until it just touches the stop arm
5. Turn the mechanical stop in an additional 1/2 turn
6. Tighten the 7mm lock nut
NOTE: In this configuration you should be able to see a little light between the throttle plate and the bore in the throttle body.
7. Set the TPS so you hear a soft 'click' just as the throttle plate opens and closes.
8. Reinstall the throttle body.
9. Adjust the throttle cable so there is just a wee bit of slack. What you want is to let the throttle plate close without any tension on the cable.
At this point you can connect a dwell/tach to the coil and start the engine. The idle should be 840 +- 50 RPM.
To set the idle RPM you need to put a jumper between pins B and C of the diagnostic connector located on the driver side fender well near the evaporative emissions control valves.
With the jumper installed, use the idle by-pass on the throttle body to set the idle to 840 RPM. Verify that the engine will return to the proper idle after 'bliping' the throttle.
Once the mechanical idle is set, remove the jumper from the diagnostics connector. The idle should not change more than a few RPM.
The easiest way to test the ISV is by turning on the A/C, headlights, and other heavy electrical loads. If the ISV is working properly the idle should drop just a tad and then come back to "normal."
I suspect that you may be dealing with the throttle body and throttle cabel being out of adjustment, combined with an idle stabilizer problem.
On the later cars like yours, idle is "set" two ways. First is the mechanical adjustment, and second is via the Idle Stabilizer Valve, or ISV.
To set the mechanical idle you need to remove the throttle body and set the mechanical stop. To do this you need to:
1. Loosen the TPS
2. Loosen the 7mm lock nut on the mechanical stop
3. Back out the mechanical stop until it is not touching the throttle plate stop arm
4. Turn the mechanical stop in until it just touches the stop arm
5. Turn the mechanical stop in an additional 1/2 turn
6. Tighten the 7mm lock nut
NOTE: In this configuration you should be able to see a little light between the throttle plate and the bore in the throttle body.
7. Set the TPS so you hear a soft 'click' just as the throttle plate opens and closes.
8. Reinstall the throttle body.
9. Adjust the throttle cable so there is just a wee bit of slack. What you want is to let the throttle plate close without any tension on the cable.
At this point you can connect a dwell/tach to the coil and start the engine. The idle should be 840 +- 50 RPM.
To set the idle RPM you need to put a jumper between pins B and C of the diagnostic connector located on the driver side fender well near the evaporative emissions control valves.
With the jumper installed, use the idle by-pass on the throttle body to set the idle to 840 RPM. Verify that the engine will return to the proper idle after 'bliping' the throttle.
Once the mechanical idle is set, remove the jumper from the diagnostics connector. The idle should not change more than a few RPM.
The easiest way to test the ISV is by turning on the A/C, headlights, and other heavy electrical loads. If the ISV is working properly the idle should drop just a tad and then come back to "normal."
