kinglenario

hey guys, i searched on this but couldn't really find anything related.

when i'm driving my car ('86 951) say in 4th gear at 50mph and let off the gas, instead of how it normally decelerates evenly, it jerks back and forth on and off the throttle lightly. the revs also fall more slowly than normal when shifting. usually these things rev down pretty quickly, and mine is just reving down a lot more slowly than normal.

i am also having a little idle issue. once it gets to full/hot temp it is worse. it will sit at about 1100 or so, then move to 900, then back and forth. it's never consistent. it's also not completely smooth. there is a very small 'blurp' every couple of seconds.

the tps switch is engaging properly. could electrical grounding be causing this? should i just check the one on the bell housing? how hard is it to get to that one?

thanks!

Zeff

Tps

Follow the LR site to reset it. Just cause it clicks doesn't mean it is set

TheLlamaGod

i had the same issue. switched out tps and dme temp sensor and now it idles and decelerates perfect. i think tps was the main problem though

kinglenario

hmmmm, so it was clicking but not doing anything? the weird thing is that it only does this when it's hot. it runs perfect for about 20 minutes until it really warms up then these symptoms start.

i just tried following lindsey's idle adjustment but it doesn't explain where to jump the leads on the idle stabilizer. it's says pins B and C but i have no idea what plug that is. without jumping the idle stabilizer i can screw the idle RPM screw all the way down and it will still go up to about 1100 then down to 900ish and back and forth.

i'll search on the DME temp sensor.

thanks!

MC951

I'm sure that you checked but is the return spring on the throttle body ok?

Jeff N.

Check to make sure the throttle cable sheathing is not slipping out of it's socket near the cable exit point. Mine was doing that 'jamming' the throttle open a bit.

Easy check.

kinglenario

no, that looks good. i think the key to figuring this one out is that it only happens when the oil temp gets to full temperature. i have to drive the car for about 20 minutes before it starts reving down slowly and the idle kicks up to about 1100 or 1200.

any ideas what the hell would cause that? is there any type of oil pressure sensor that doesn't allow the engine to idle down if it doesn't think it sees enough pressure? just an idea.

thanks!

Tom M'Guinn

I'd guess that the TPS/motor is just heating up and expanding and causing the TPS to malfuntion. It's not uncommon for electronics to work ok when cool but malfunction when hot. Clarks-garage has a good diagnostic write up too, though it may not help if your tps is failing intermittently when it gets hot. There is no oil-pressure based idle control.

951kaos

Had the same problem; replaced the TPS and it ran fine. It probably has a bit of dirt/carbon from wear that throws it off after it gets hot; even when setup properly.