Ronnie Posted September 27, 2017 Share Posted September 27, 2017 This has only occurred twice so far, on two separate days, but I expect it to happen again. The engine is fully warmed up and running normally when it happens. The first time it happened was about a week ago when I accelerated to pass a car quickly and then let off to pull back in front of the car I had passed. The engine seemed to keep accelerating. Not at the same rate it was accelerating when I had my foot on the gas. The second time it did it was just once on Saturday while accelerating out of a long sweeping curve where I went to the floor with the gas for a few seconds and then let off. The car was still pulling even though I was going uphill but I could easily slow it down with the brakes. Both times it felt the same. It's like the engine runs at a really fast idle and wants to keep pulling the car for some reason. I can still slow the car down easily with the brakes but it's still a little scary. Scary enough that I'm prepared to turn off the ignition of needed. This fast idle seems to last for a short time, maybe a minute or so and then it goes way for no obvious reason. Each time it happened I tried stomping around on the gas pedal thinking it was a sticking throttle linkage but that made no difference. Each time after I got home I toughly inspected all the throttle components for something sticking and found nothing. I'm going to have to dig deeper. What do you guys think? Sticking IAC or EGR? Any ideas would be appreciated. Link to comment Share on other sites More sharing options...
2seater Posted September 27, 2017 Share Posted September 27, 2017 The only thing I can think of that will allow the engine to run at higher rpm would be airflow. It is normal for the IAC to increase counts as the throttle is pressed while running which I always ASSumed was to catch the throttling to let the engine down under control rather than it seeing the effect of the throttle slamming shut. You can monitor the IAC counts while driving to see what it is being commanded to do. The other possibility would be a vacuum leak, maybe the PCV? Link to comment Share on other sites More sharing options...
retired mechanic74 Posted September 27, 2017 Share Posted September 27, 2017 This has only occurred twice so far, on two separate days, but I expect it to happen again. The engine is fully warmed up and running normally when it happens. The first time it happened was about a week ago when I accelerated to pass a car quickly and then let off to pull back in front of the car I had passed. The engine seemed to keep accelerating. Not at the same rate it was accelerating when I had my foot on the gas. The second time it did it was just once on Saturday while accelerating out of a long sweeping curve where I went to the floor with the gas for a few seconds and then let off. The car was still pulling even though I was going uphill but I could easily slow it down with the brakes. Both times it felt the same. It's like the engine runs at a really fast idle and wants to keep pulling the car for some reason. I can still slow the car down easily with the brakes but it's still a little scary. Scary enough that I'm prepared to turn off the ignition of needed. This fast idle seems to last for a short time, maybe a minute or so and then it goes way for no obvious reason. Each time it happened I tried stomping around on the gas pedal thinking it was a sticking throttle linkage but that made no difference. Each time after I got home I toughly inspected all the throttle components for something sticking and found nothing. I'm going to have to dig deeper. What do you guys think? Sticking IAC or EGR? Any ideas would be appreciated. You may want to take a good hard look at your Cruise Control I've seen this same symptom on other GM makes. Even when the cruise is not engaged. If it becomes more predominant I would disconnect the cruise cable and see if it stops accelerating. Link to comment Share on other sites More sharing options...
Ronnie Posted September 27, 2017 Topic Author Share Posted September 27, 2017 The PCV is a good possibility that I hadn't thought about. I have one on hand that I was going to install this winter. The next time I will try to monitor the IAC. The last two times it happened was in heavy traffic and in a lot of curves which made it hard to manipulate the CRT. I hope the next time is will happen in an area that has little traffic so I can go into diagnostics and take a look to see what the IAC is doing. Link to comment Share on other sites More sharing options...
Ronnie Posted September 27, 2017 Topic Author Share Posted September 27, 2017 You may want to take a good hard look at your Cruise Control I've seen this same symptom on other GM makes. Even when the cruise is not engaged. If it becomes more predominant I would disconnect the cruise cable and see if it stops accelerating. That's a good idea. I did think to turn off the cruise control button while it was doing it but that made no difference. I will check the cruise control cable for binding or sticking. Link to comment Share on other sites More sharing options...
harry yarnell Posted September 30, 2017 Share Posted September 30, 2017 Ronnie brings up the PCV. The PCV grommet can get brittle and disintegrate, causing an undesireable air leak. Link to comment Share on other sites More sharing options...
Ronnie Posted September 30, 2017 Topic Author Share Posted September 30, 2017 Ronnie brings up the PCV. The PCV grommet can get brittle and disintegrate, causing an undesireable air leak. I think you might be correct in that my grommet is brittle and may be coming apart. I can't tell much by looking because it is in a hard location to see it good. I've decided if it will make it until winter when I rarely drive that I will change intake gaskets and the PCV/gommet at the same time. I hate to tear into it during the fall when I enjoy driving my Reatta the most. Link to comment Share on other sites More sharing options...
ski.dive Posted September 30, 2017 Share Posted September 30, 2017 I think you might be correct in that my grommet is brittle and may be coming apart. I can't tell much by looking because it is in a hard location to see it good. I've decided if it will make it until winter when I rarely drive that I will change intake gaskets and the PCV/gommet at the same time. I hate to tear into it during the fall when I enjoy driving my Reatta the most. Ronnie, Heads-up I went thru 5-6 different grommets, before I found the correct fit grommet, that slid right into the hole. Link to comment Share on other sites More sharing options...
Ronnie Posted September 30, 2017 Topic Author Share Posted September 30, 2017 Ronnie, Heads-up I went thru 5-6 different grommets, before I found the correct fit grommet, that slid right into the hole. I remember that. That is one of the reasons I was waiting until winter to try to change it. I will be contacting you for advice if I run into problems when I change it. Link to comment Share on other sites More sharing options...
ski.dive Posted September 30, 2017 Share Posted September 30, 2017 I remember that. That is one of the reasons I was waiting until winter to try to change it. I will be contacting you for advice if I run into problems when I change it. Here is where I found it: http://www.highwaystars.net/search.php?S...ry=1254119 Link to comment Share on other sites More sharing options...
Ronnie Posted September 30, 2017 Topic Author Share Posted September 30, 2017 Here is where I found it: http://www.highwaystars.net/search.php?S...ry=1254119 Thank you! Link to comment Share on other sites More sharing options...
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