Need help. Was trying to fix bad idle, now car won't stay running.
11-19-10, 12:35 PM
#1
Need help. Was trying to fix bad idle, now car won't stay running.
I'll try and put as much info as I can as i've been working on this for a while.
The car was having idle problems and would not do it's warm up when you turned it on (3k, 1.5k, 750rpm). It would go right to 1,500 and go up and down about 150 rpms. I checked the FSM and the haynes manual and went over most of the stuff. I tried lowering the idle on the throttle body and it's already as low as it can go. I checked for vacuum leaks and there do not seem to be any, but there could be one that I cannot see. I did blast it with some carb/parts cleaner and the idle did not jump anymore than it already was.
I was going to adjust the timing, but it was not do able as the advance was making it difficult when I shone the timing gun on it. I did set it to TDC and restabbed the crank angle sensor per the FSM's instuctions just to get rolling.
I thought it was the thermowax and did the test where you submerge it in 140 degree water to see if the rod extends and it passed. I did not notice till I took it apart that the hose going from the back of the throttle body down to the block had a crimp in it that was not letting water pass. The hose from the BAC going to the thermowax was hot and the hose going down to the block was cold so I got some 3/8" hose and replaced it. Water was again flowing through the thermowax.
But, the car will not start. I drove it down to the parts store before replacing the hose, but after that it would not stay running. It was very hard to start up and I had to floor it to keep it running. I know it is probably the timing, but I just did that whole thing with restabbing the crank. I will go and check the resistance on the plug like it says in the FSM, but what I'm looking for is some advice.
The car does have fuel. The plug to the afm is hooked up. The injectors are hooked up. It will turn over, but not stay running unless you keep your foot in it.
Also, I tried adjusting the fast idle cam on the back of the throttle body after I took the thermowax off to do the test. Would that make a big difference in the car not starting? I'm not really sure where the lobe is supposed to be at when the car is cold. It says 0 degrees fahrenheit on the right mark in the FSM, but if I set it there, it would come off the cam when it warmed up as the cam moves clockwise when the car warms up.
Anyways, feel free to drop some suggestions and thanks in advance.
The car was having idle problems and would not do it's warm up when you turned it on (3k, 1.5k, 750rpm). It would go right to 1,500 and go up and down about 150 rpms. I checked the FSM and the haynes manual and went over most of the stuff. I tried lowering the idle on the throttle body and it's already as low as it can go. I checked for vacuum leaks and there do not seem to be any, but there could be one that I cannot see. I did blast it with some carb/parts cleaner and the idle did not jump anymore than it already was.
I was going to adjust the timing, but it was not do able as the advance was making it difficult when I shone the timing gun on it. I did set it to TDC and restabbed the crank angle sensor per the FSM's instuctions just to get rolling.
I thought it was the thermowax and did the test where you submerge it in 140 degree water to see if the rod extends and it passed. I did not notice till I took it apart that the hose going from the back of the throttle body down to the block had a crimp in it that was not letting water pass. The hose from the BAC going to the thermowax was hot and the hose going down to the block was cold so I got some 3/8" hose and replaced it. Water was again flowing through the thermowax.
But, the car will not start. I drove it down to the parts store before replacing the hose, but after that it would not stay running. It was very hard to start up and I had to floor it to keep it running. I know it is probably the timing, but I just did that whole thing with restabbing the crank. I will go and check the resistance on the plug like it says in the FSM, but what I'm looking for is some advice.
The car does have fuel. The plug to the afm is hooked up. The injectors are hooked up. It will turn over, but not stay running unless you keep your foot in it.
Also, I tried adjusting the fast idle cam on the back of the throttle body after I took the thermowax off to do the test. Would that make a big difference in the car not starting? I'm not really sure where the lobe is supposed to be at when the car is cold. It says 0 degrees fahrenheit on the right mark in the FSM, but if I set it there, it would come off the cam when it warmed up as the cam moves clockwise when the car warms up.
Anyways, feel free to drop some suggestions and thanks in advance.
11-19-10, 12:54 PM
#3
Now With 10th AE Fun!
iTrader: (1)
Join Date: Jun 2005
Location: CA
Posts: 1,869
Likes: 0
Received 0 Likes
on
0 Posts
If you know for sure you have fuel maybe check the voltage to the pump at the fuel pump connector near the rear shock tower to see if it's low. A large vac leak will not allow it to start either which is more of what it is sounding like with the rough idle.
11-19-10, 12:55 PM
#4
The 3000 rpm startup only occurs when the temp switch screwed into the bottom of the radiator senses a temperature above 65 degrees or so. If the temp is below that then it won't engage at startup. This is how it's supposed to work. There might be other issues as to why it is not working.
When the car started and ran at 1500 rpm with the small surging going on did it do this just for a period of time until the engine warmed up or did it do it constantly? Which part of the fast idle cam did you adjust. Was it just the screw that touches the thermowax plunger? The use of boiling water is to test not just if the plunger extended but more to the point of whether the roller pin rolled fully off the cam or not.
EDIT:
The roll pin on the fast idle cam is supposed to roll off or disengage from the cam as the car warms up as this is what allows the primary plate opening to close and in doing so therefore drop the idle speed.
When the car started and ran at 1500 rpm with the small surging going on did it do this just for a period of time until the engine warmed up or did it do it constantly? Which part of the fast idle cam did you adjust. Was it just the screw that touches the thermowax plunger? The use of boiling water is to test not just if the plunger extended but more to the point of whether the roller pin rolled fully off the cam or not.
EDIT:
The roll pin on the fast idle cam is supposed to roll off or disengage from the cam as the car warms up as this is what allows the primary plate opening to close and in doing so therefore drop the idle speed.
11-19-10, 01:03 PM
#5
Is your throttle cable too tight?
How did you set your tps? I had better luck via the test light method.
Will the car start, or will it just not idle correctly?
When was the last time you did a compression test?
What do your spark plugs look like, are they wet?
How did you set your tps? I had better luck via the test light method.
Will the car start, or will it just not idle correctly?
When was the last time you did a compression test?
What do your spark plugs look like, are they wet?
11-19-10, 01:10 PM
#6
The 3000 rpm startup only occurs when the temp switch screwed into the bottom of the radiator senses a temperature above 65 degrees or so. If the temp is below that then it won't engage at startup. This is how it's supposed to work. There might be other issues as to why it is not working.
When the car started and ran at 1500 rpm with the small surging going on did it do this just for a period of time until the engine warmed up or did it do it constantly? Which part of the fast idle cam did you adjust. Was it just the screw that touches the thermowax plunger? The use of boiling water is to test not just if the plunger extended but more to the point of whether the roller pin rolled fully off the cam or not.
When the car started and ran at 1500 rpm with the small surging going on did it do this just for a period of time until the engine warmed up or did it do it constantly? Which part of the fast idle cam did you adjust. Was it just the screw that touches the thermowax plunger? The use of boiling water is to test not just if the plunger extended but more to the point of whether the roller pin rolled fully off the cam or not.
I had to pull the UIM last night to get the hose on so I might just pull it again and make sure I have everything hooked up correctly.
Also, the cream colored part that is attached to the thermowax had a bung break off. It's the part that goes over to the dashpot.
I have another one off an automatic I can swap on, but it has 3 ports instead of 2. From what I can tell from the FSM it works the same way, just has another port instead of a cap, but I could be wrong.
So, the roller pin is supposed to roll off of the cam at some point? I'm having a bit of trouble deciphering the FSM at some parts.
11-19-10, 01:20 PM
#7
It was also set with the car warmed up, turned off with the key in the "on" position, and disconnected from the harness.
The car will start/turn over/run just fine, but it will not stay running. To me it feels like a timing issue or maybe bad spark plugs (which i'm gonna pull after I write this reply).
I have not done a compression test recently, but I did use a block tester and it did not change colors when I hooked it up so it seems pretty sound.
I forgot to mention that the motor was rebuilt about 20k miles ago.
Throttle cable is ok too. It's got a little slack to it.
Trending Topics
11-19-10, 01:21 PM
#8
What was the idle speed though after the car was fully warmed up? The surging is likely a TPS in need of adjustment or perhaps a vacuum leak.
The roller pin disengages from the cam the idle should be pretty close to 750 rpm if all other things were set properly.
The Auto thermovalve could be used but the hose that leads to the double throttle diaphragm really isn't needed and should be capped.
The idle adjust screw at the top of the throttlebody being screwed all the way in would lower the idle speed by cutting off an air supply within the dynamic chamber. Backing off on that screw would be a good idea.
EDIT: The broken bung will cause a vacuum leak.
The roller pin disengages from the cam the idle should be pretty close to 750 rpm if all other things were set properly.
The Auto thermovalve could be used but the hose that leads to the double throttle diaphragm really isn't needed and should be capped.
The idle adjust screw at the top of the throttlebody being screwed all the way in would lower the idle speed by cutting off an air supply within the dynamic chamber. Backing off on that screw would be a good idea.
EDIT: The broken bung will cause a vacuum leak.
11-19-10, 01:41 PM
#9
What was the idle speed though after the car was fully warmed up? The surging is likely a TPS in need of adjustment or perhaps a vacuum leak.
The roller pin disengages from the cam the idle should be pretty close to 750 rpm if all other things were set properly.
The Auto thermovalve could be used but the hose that leads to the double throttle diaphragm really isn't needed and should be capped.
The idle adjust screw at the top of the throttlebody being screwed all the way in would lower the idle speed by cutting off an air supply within the dynamic chamber. Backing off on that screw would be a good idea.
EDIT: The broken bung will cause a vacuum leak.
The roller pin disengages from the cam the idle should be pretty close to 750 rpm if all other things were set properly.
The Auto thermovalve could be used but the hose that leads to the double throttle diaphragm really isn't needed and should be capped.
The idle adjust screw at the top of the throttlebody being screwed all the way in would lower the idle speed by cutting off an air supply within the dynamic chamber. Backing off on that screw would be a good idea.
EDIT: The broken bung will cause a vacuum leak.
Here's what I'm thinking: the crimped hose going from the thermowax on the back of the throttle body was cutting off the circulation and the roller pin was not coming off the cam lobe. When I replaced the hose it was completely dry after the crimp and down at the block the bung was loaded with rusty poop that I had to free with a screwdriver. As soon as I freed it, coolant shot out of the hole about 3 feet. I've since replaced the coolant and it is topped off.
I also pulled the plugs and they are fouled. I'm gonna ride my bike down to Autozone and get some new leading plugs, then swap over the thermovalve.
11-19-10, 01:44 PM
#10
Use the link to show you which nozzles of the thermovalve you need or don't need. Post #6 is gold!
https://www.rx7club.com/showthread.p...ttle+diaphragm
EDIT:
The TPS needs to be set not just with engine warm but the idle at the proper speed and the FSM states that the G/R wire running from the sensor to the TPS should be 1 volt.
https://www.rx7club.com/showthread.p...ttle+diaphragm
EDIT:
The TPS needs to be set not just with engine warm but the idle at the proper speed and the FSM states that the G/R wire running from the sensor to the TPS should be 1 volt.
11-19-10, 03:20 PM
#11
Use the link to show you which nozzles of the thermovalve you need or don't need. Post #6 is gold!
https://www.rx7club.com/showthread.p...ttle+diaphragm
EDIT:
The TPS needs to be set not just with engine warm but the idle at the proper speed and the FSM states that the G/R wire running from the sensor to the TPS should be 1 volt.
https://www.rx7club.com/showthread.p...ttle+diaphragm
EDIT:
The TPS needs to be set not just with engine warm but the idle at the proper speed and the FSM states that the G/R wire running from the sensor to the TPS should be 1 volt.
I got some new leading spark plugs and popped them in and the car shot up to 3k and stayed there for a few seconds and then the rev's dropped and it died. I think it need to pull the throttle body again and reset everything back to factory regarding the fast idle cam.
Good thing I just made a pot of coffee.
p.s thank you everyone for your help. I'm doing my best to work on the car and reply at the same time.
11-19-10, 04:02 PM
#12
Kinda got it running, but it dies right away. I've convinced myself that I knocked something loose when I pulled the UIM last night so I'm gonna pull it again and check all the connections underneath to put my mind at ease and cross some things off my list.
11-21-10, 11:51 PM
#13
Just an update...
I got the car running. I found that the water thermo sensor on the thermostat housing was hanging on by one wire and was not working so I got a new one. Then I taped up the water sensor on the throttle body so it would plug up the vacuum leak and it ran through the warm up procedure as usual before settling down to around 800 rpms. I set the timing, then the tps, then repeated. I took it out for a test drive and everything was running just fine til I got home and it was not idling well.
I popped the hood and was checking the timing and noticed some smoking coming from the passenger side. After checking it out with a flashlight I noticed that the left visible injector ( not the one under the UIM) was leaking from the fuel rail. I stopped the motor and pulled it and the O-ring is shot. I'm going to get some tomorrow at the parts store and see if that solves my problem.
Thanks everyone for helping me out. I think I got a few more grey hairs over this and hopefully I will get it worked out tomorrow.
I got the car running. I found that the water thermo sensor on the thermostat housing was hanging on by one wire and was not working so I got a new one. Then I taped up the water sensor on the throttle body so it would plug up the vacuum leak and it ran through the warm up procedure as usual before settling down to around 800 rpms. I set the timing, then the tps, then repeated. I took it out for a test drive and everything was running just fine til I got home and it was not idling well.
I popped the hood and was checking the timing and noticed some smoking coming from the passenger side. After checking it out with a flashlight I noticed that the left visible injector ( not the one under the UIM) was leaking from the fuel rail. I stopped the motor and pulled it and the O-ring is shot. I'm going to get some tomorrow at the parts store and see if that solves my problem.
Thanks everyone for helping me out. I think I got a few more grey hairs over this and hopefully I will get it worked out tomorrow.
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
07-01-23 04:40 PM
rkhanso
2nd Generation Specific (1986-1992)
1
08-13-15 11:40 AM
