'90 idle too high

[Jim]

I have been driving a '90 for the winter that sat for about 3 years. The idle is about 1400 RPMs in park. I don't remember if I had this problem when I was using the car 3 years ago but suspect not.

Very good vacuum.

Changed MAS

Changed  IAC.

Changed EGR. ( thought this was going to correct the problem as there was no gasket there but replaced EGR and a gasket, still high idle. )

No codes.

I may change today the TPS but am not hopeful.

( it is nice to have lots of parts cars.   )

 

Any suggestions?

 

Jim

 

[padgett]

What are the TPS position (ED01) and IAC command (ED22) doing ? Should be .38-.42v at idle and over 4.0v at WOT. IAC is in steps.

[2seater]

This subject seems to be coming up fairly regularly now but the solutions seem to be all over the place. Can you reduce the idle by overriding the IAC? My '89 that became the parts car would do that after long storage too. I could force it lower, and it would stay there, but would possibly do it again after a restart. I never pursued it very hard after that because it wasn't being driven. Check the TPS in diagnostics to see what it is now.

[Ronnie]

Jim, Check out this topic. You might find it helpful.

 

ECM/IAC - Not an ideal idle

 

 

[Jim]

Ronnie,

You may have hit the nail on the head with your link.

I do have too high power steering pressure. When I drove the car a few years ago the steering was too easy. At that time I was worried I might blow a hose or seal or something but nothing ever went wrong so I left it. The steering is still way easier than any other Reatta I have ever driven.

Padgett, Thanks for the EDxx settings. I have not looked at how to get them for a long time but will refresh my learning and look at them but I think first I will look at the power steering situation and see why my pressure is too high causing the steering to be too easy and probably the cause of my high idle.

Thanks everyone.

Jim

 

Follow up 15 minutes later.

I need to get on this high pressure problem asap as I just remembered yesterday I had to add some PS fluid. This means I definitely have a leak and hopefully if I lower the pressure right away the leak will not get worse or maybe hopefully will stop. The last thing I want to do is change a rack and pinion on a Reatta. I have a spare on the shelf but this is not an fun/easy job.

Edited February 19, 2021 by Jim (see edit history)

[Jim]

Heading back out now to look further into the problem.

I should have looked at the ED codes first as that would have saved me some time previously.

I did change the PS pump and no difference. I disconnected the PS pressure sensor and no difference.

I then did the EDs and have multiple issues. I do have a too high ED01, TPS mine is reading .058

I have an ED20  Block Learn Memory of 150. That supposedly means I have a bad ground at the ignition module. I took off the module, cleaned all the surfaces and put on a different module and still 150. Need to trace this ground.

My ED21 Air Flow is supposed to be 4-7 and mine is varying 86-90.

My ED 22 IAC supposed to be 10-50 mine is 71. I did last week replace the IAC but I am thinking if I fix the ED01 then this code might get better.

My ED23 MAT says it varies but mine is on 0.

[padgett]

First adjust the TPS to be .38-.42. High TPS will cause a high idle.

[2seater]

Block Learn is long term fueling, 150 indicating it is adding fuel because it sees a lean condition. If the engine is not fully warmed up and in closed loop, ignore that number for now. I agree the TPS should be addressed first. Either it is bad, out of adjustment or something is binding and not allowing the throttle to fully close. Has the throttle stop screw been tampered with?

[jonlabree]

Jim, I had the same probleme a few months ago.

I also replaces all sensors with no luck.

Check and adjust your TPS reading, THen check the resistance of your IAC.

Mine was new and it had a bad reading on one side.

Good luck.

[Jim]

Thanks everyone for the thoughts. 

It was the TPS.

First I tried adjusting it and naturally I went the wrong way. I went the other way and still .058. Adjusted it more and the reading went down to .018 and the idle went right down to normal. I then tried adjusting it up a little but it went right up to the .058. I then replaced the TPS and after a couple of adjustments I now have .038 and a nice idle. The '90 manual shows it should be between .033 and .046.

My ED21 and 22 were out of spec but now with a good TPS they fell right into place.

There is an asterisk/foot note saying if the ED20 is 150 it is a fuel code but it says there could be bad ground at the ICM. I do have good grounds there and the car runs fine so I am going to just ignore that reading. The car was warmed up and in closed loop.

A little side note on what I learned is the IACs are '88-90 and '91 is different. The MAS also '88-90 with '91 different but the TPS is the same '88-91.

 

[Buick City]

I to have this problem! I got everything dialed in,and it ran great the next day going to work,but going home the tps was back to its old tricks ! it is new,and adjusted to .33. maybe I will go lower & see what happens .The only code I have is e22. I had the same problem with the super - easy power steering !  I took it for a 400 mile test drive and I had to hang onto the wheel as it wanted to oversteer ! I took it to get aligned,as I put new struts & engine cradle mounts & stabilizer bars on it & they told me they could not do it , as the rack & pinion was shot!  It was not a fun job,but now steers great!

[2seater]

On 2/22/2021 at 12:04 PM, Jim said:

Thanks everyone for the thoughts. 

It was the TPS.

First I tried adjusting it and naturally I went the wrong way. I went the other way and still .058. Adjusted it more and the reading went down to .018 and the idle went right down to normal. I then tried adjusting it up a little but it went right up to the .058. I then replaced the TPS and after a couple of adjustments I now have .038 and a nice idle. The '90 manual shows it should be between .033 and .046.

My ED21 and 22 were out of spec but now with a good TPS they fell right into place.

There is an asterisk/foot note saying if the ED20 is 150 it is a fuel code but it says there could be bad ground at the ICM. I do have good grounds there and the car runs fine so I am going to just ignore that reading. The car was warmed up and in closed loop.

A little side note on what I learned is the IACs are '88-90 and '91 is different. The MAS also '88-90 with '91 different but the TPS is the same '88-91.

 

Regarding the MAF, IAC  and TPS; is it just the difference in form or shape that makes them different or do they operate differently? I have adapted the '91 throttle body and MAF combination to a couple of different engine configurations in my '90 and the stock ECM has had no issue with operating either style throttle body combination of TPS, MAF or IAC? Just a clarification question.