riffman12

Hey guys,

Couple of issues with my relatively new to me 86 Turbo. Wondering if perhaps they are related.

1) When the engine gets warm (stop and go around town driving) my idle is creeping up to 1200-1500rpm. When it does this and I lift my foot off the throttle to decelerate I can feel little dabs of throttle being inputted as if I'm poking at the throttle (but I am not).

Doesn't do this when it is cold or after long periods of freeway driving. The TPS is clicking "off" when the throttle is released and the cable is not getting hung up anywhere (I actually need to tighten it a bit). I intend to get the intake manifold off soon and check my Idle Valve, but I am wondering if this problem is related to my second issue:

2) I'm having the notorious hot start issue. Car fires right up when cold. Car takes 3-5 seconds of starter cranking to start when hot. Once started the idle is perfect and doesn't jump around or anything. It always starts, just takes some time when hot.

I'm about to order a new DME relay as that seems to be the first place to go with a hot start issue. Is the relay the same for the Turbo and the NA cars? I don't see a "turbo specific" DME relay on pelican.


Is there any chance these two issues are linked? Or is it just coincidence and they are both common issues on the cars?

Only other real piece of info regarding the situation is that my mechanic said my car was running a tad rich so he leaned it out a bit. O2 sensor is fine.

Any help would be greatly appreciated. Apologies for the novel

travisgreen

I would try a temp sensor, they are about 15 bucks at autozone. It may be getting to much fuel when hot which leads to extended cranking.

travisgreen

also, how did your mechanic "lean it out a bit" ?? if its running rich when hot and hard to start when hot its more than likely your temp sensor

riffman12

You mean the DME temp sensor? I can try that, is it pretty straight forward to replace? And do you think that could also be causing the high idle? Or just the hot start issue?

He said he gave the screw on the air fuel meter a bit of adjustment when he found it was running a tad rich.

travisgreen

that screw is a process in setting idle, not to lean out the car when its a tad rich. If this is an actual mechanic and decided to mess with that screw instead of look at the temp sensor you may want to find another mechanic. Yes its VERY straight fwd. unplug, unscrew replace replug. this will solve your issue. yes that is why its idling high when hot.... also , now you will have to reset your idle with the proper steps since your mechanic decided to start messing with stuff

Dougs951S

maybe a stupid question, but have you checked to see that your cable isnt binding and the TPS is clicking on the idle contact AFTER the engine is hot and the idle has climbed? I chased the same issue for a while until one day I popped the hood after being on the highway for 2 hours and getting the motor nice and hot. The car was idling at about 1200 rpm. I grabbed the throttle cam and it instantly dropped down to a nice 900 rpm idle. I found out that when the throttle cable got real nice and hot, it was pulling the cam up just enough to not let it close the idle contact. I loosened the cable ~1/10 of a turn on the adjuster nut and its never given me an issue since. perfect 900 rpm idle at all times.

travisgreen

im more apt to think its a sensor since its been running rich, if you unplug a working sensor when the car is warm the idle will climb bc its now getting more fuel than it sould be at idle but not more air, that's why its rich

riffman12

Yeah I've tried that. No Dice

The throttle cam gets quite hot haha

Hmm OK. I'll try the sensor, thanks!

I think I might order a new DME relay regardless to keep in the car as a spare. The 944 NA and Turbo use the same relay correct?

travisgreen

I believe so

URG8RB8

Take cover off of your DME relay and reflow the solder on the solder pads with some good rosin core solder. Clean residue with electronics cleaner and toothbrush put back together and most likely hot start issue will be gone.

riffman12

I think I'm going to buy a new relay just so I have a spare, but I will try that with the one I take out. Thanks!

URG8RB8

I don't blame you for buying a new DME, but as you will learn most likely they are 20+ years old too and have the same flaw. I carried around a "new" spare in case I had an issue with the original. When it did go bad, I plugged in my "new" and Wha Lah, same problem. This led me down a slippery slope needlessly. Changing many good parts that I did not need too. Finally, I read the post from Texas Blake and reflowed the pads on both relays and what do you know, they both work fine now!!! If you buy a new one, I would still reflow the pad with new good solder. It is a design flaw.

travisgreen

update??

riffman12

Update:

Changed the DME Relay, did not fix anything. The high idle is still an issue, but not any worse than it was.

However, I replaced my DME temp sensor yesterday and, if anything, the hot start problem has gotten worse. Now on hot starts it cranks and starts and really idles badly and sometimes stalls completely. It had done this a few times before changing the sensor, so hard to say if the sensor change made it worse. It fires up perfectly on a cold start. Still runs perfectly when up and running after a hot start (except for high idle).

One other question about the DME sensor: The old sensor had a "tooth" to stop it being plugged in upside down. The new one did not so I just guessed. If the plug is upside down, will it still work? Is it directional?

One other thing to note, pulled an intercooler pipe and could smell gas in it (car was cold).

Are these symptoms pointing more to a leaking injector?

Sorry I know that's a lot of info. I'm still loving the car, but these issues are getting quite annoying.

Lex_GTX

The high idle when hot is likely a failing TPS. Even if it clicks the switch is likely not closing.