I have a friend who is going to "give" my son a car. Long story. Anyway, my uncle and I just went over to take a look at it. She had originally parked it a year ago thinking there was a transmission problem. I don't think so based on what we saw/heard today. The idle is EXTREMELY high. We turned it down as far as it would go. It's like it'll rev down and then rev back up. Even when it's ideling down, it's still too high. I think this is why she thought it was the transmission because when it's that high, it jerks when changing into another gear. It probably was revving up as she was driving it and the RPM's were too high and it scared her (she's young). Sometimes, in some gears (it's an automatic), it would calm down, but then you would put it back in that gear, and it would rev back up again. There was no rhyme or reason. It was like *something* was telling it to do it. Is there a sensor or something? It is a 1990 740 GL.

I'd like to find something "simple" to check, if ya'll have any suggestions, before I make any decisions.

Please help!!

Thanks!

 

From looking also at your other post.....take the car! They are durable and simple. The problem sounds like a dirty throttle body, dirty idle control valve and/or mis-adjusted throttle position switch. All easy to do. The throttle body is right behind where the intake air snorkel attaches, held by three 13mm nuts. The TPS comes off with it. The best manual for the DIY'ers is the Bentley manual that covers the 83-93 240 series. Pretty much all of the engine managment stuff is the same for the 740. Haynes and Chilton's make one for the 700/900 series, but are about worthless.

 

Thank you so much! This is a great help! I was actually going to go buy one of those books today, but your recommendation of which one is priceless, thank you!

I still have one remaining question. If we try to clean it versus replacing it first, what is the best thing to clean it with? I'm very anxious to see how the car runs once we get that idle down so am looking for the least expensive way to do it. If later we need to replace it, so be it.......... but a temporary fix would be nice to be able to drive it home, etc.

Thanks again!!

 

You shouldn't have to replace it. Pop off the air horn, and use Throttle Body/Fuel injector cleaner and spray carefully ( do not get any in or on the throttle position sensor), then scub with an old toothbrush or clean rag for heavy deposits. The IAC is under the intake manifold , the two hoses and one wire bail connector. Hold it with the entrance holes down, spray the inside with the other hole covered, shake then pour out the gunk. Repeat until clean. The spring loaded cylinder inside should be free and move back and forth when it is shaken side to side.

 

Got 'cha!! THANK YOU!!!! Wish me luck!!!
The girl also ripped out the whole panel for the air conditioner, heat controls, etc., trying to get her stereo out so all of that has to be hooked back up correctly (luckily she saved everything......... well except for the screws..... lol). She was going to just JUNK this car because she thought it needed a transmission so she went out and bought a new Honda. So all of that will have to be put back, an exhaust leak addressed, and the rear brakes are scraping, but it's also been sitting a year so they might be rusted from sitting so long. But these things are minor compared to a new transmission. If we can get this idle down as simply as you seem to think we can, that will be half the battle to getting it somewhere else to get the other stuff fixed.

Now what to do with the chiggers I now have from being out there in the boonies playing around with that car yesterday!! LOL!

You've been a gem. Thanks again!