The Oldsmobile Connection

88delta88 · Joined: 09 Jun 2003 Posts: 2407 Location: Canada

My car has ALWAYS idled roughly, since I bought it. It drives beautifully, and the engine is very strong, with only 130,000 km's on it (just over 70,000 miles I think). The problem is missing while idling.

I have done the following to no avail:
-new spark plugs, gapped to spec.
-new set of spark wires
-cleaned injectors to no end...
-fuel filter is fine
-oil is always clean as a whistle, but I did an engine flush anyways (thought something might be sticking in the lifters...)
-checked the crankshaft position sensor
-checked the camshaft position sensor
-had to change the timing gears and chain, the chain slipped on the aluminum gear for the camshaft, rounding off all the teeth. (kinda thought that would fix it for sure, but not)

No success. Engine runs very smooth when it is cold. The rough idle isnt really bad, but its annoying. Doesnt die when I shift from park, which is common among idle problems...

Havent yet looked at the PCV valve yet, but should that affect it?

Any ideas would be better than what I can think of...
Thanks,
Aaron

73Delta88 · Posted: Fri Jun 13, 2003 6:58 pm Post subject:

I had a 93 Regency 98 with a 3.8 that ran perfect when you had your foot on the gas, but started hard and idled pretty rough... turned out to be nothing but a vacuum leak. ran perfect after that. the car is still in the family 170,000+ miles and still going strong with NO major repairs to the engine. it's a pretty ugly car in my opinion, but it's definitely been very reliable and low maintnance. and it'll get up and go pretty good considering how high it's geared.

Primer Death · Joined: 08 Jun 2003 Posts: 102 Location: Maine

I'd check the PCV valve, my car does the same

strokercutlass · Joined: 09 Jun 2003 Posts: 379 Location: Wis

actually, the majority of the 3.8's with higher mileage have this problem..rough running condition at idle, which smooths out when they come off idle and throughout the powerband....not a real easy cure that i'm aware of....seems to be a problem related to the 3.8 engine family specifically....could be a number of things, weak cylinder pressure, weak injector, slightly burned valve...as i said..this IS a common problem, without a real easy cure..my best advice is unless its REALLY bad...dont worry about it

88delta88 · Joined: 09 Jun 2003 Posts: 2407 Location: Canada

I wouldnt expect that its anything easy to spot, either. Friend has a 92 delta 88 with the same motor (i think its series II though), and my mom's 93 pntiac transsport with the same motor aswell, they run VERY smooth. But its not serious, just kinda annoying.

Will maybe get a vacuum tester, and test for leaks just out of curiosity. I have the vacuum operated vent control switch. I hate those things, maybe its leaking or something. Or maybe it just can't be fixed, which I can live with.

strokercutlass · Joined: 09 Jun 2003 Posts: 379 Location: Wis

88 delta..from what i've seen in my won experiences, it seems to be more prone in the series 1 engines...dunno if its something that was changed in the series 2 design or not.....

88Ciera_SC · Joined: 10 Jun 2003 Posts: 199 Location: Columbus Ohio

Just want to add that my 88 Ciera 3.8L has a rough idle too..
I talked to my father, the original owner ,and he said it always had a funny idle but the car runs great..

i say it is normal as long as it doesn't stall...

Spinmaster30 · Joined: 09 Jun 2003 Posts: 4 Location: Michigan

all of the 3.8l engines had a rough idle. it was the way that the engine was calebrated and there is nothing to do about it.

88Ciera_SC · Joined: 10 Jun 2003 Posts: 199 Location: Columbus Ohio

you got a picture of the decal???

Brando · Joined: 06 Jun 2003 Posts: 3067 Location: Michigan, USA

I have a pic, I'll post it in the album!

Also, my 3.8L idles rough too.... :roll:

TOC Admin
Brando

Psyco Diver 69 · Joined: 21 Sep 2003 Posts: 207 Location: South NJ

My old cutlass had the same problem then I found out I needed a new choke puller (thats the names, it is a vacume diaphram) and it helped my rough idle alot

Hans · Joined: 28 Aug 2003 Posts: 156 Location: Pocatello, Idaho

Yeah it is a really normal problem with teh series 1's. I guess it was a combination of issues. Although I know the previous owner of my car had a sensor replaced and it greatly improved the idle.

88delta88 · Joined: 09 Jun 2003 Posts: 2407 Location: Canada

Here's what I did to solve my rough idle problem (or at least make it 2 times better). I bought some of that slick 50 for older engines, and used it. Wow. After a day driving with the stuff in, the engine was noticeably more perky, sounded stronger and also idled like it should! That stuff is great! Would definately recommend it!

That doesnt exactly explain why an engine with 75,000 miles on it idled like that... The engine does not burn a drop of oil, so I dont think its low compression. I think it had more to do with the valve train somewhere... anyone offer an explaination?

Psyco Diver 69 · Joined: 21 Sep 2003 Posts: 207 Location: South NJ

This explains why the motor has a rough idle http://home.flash.net/~rjgeorge/NAnotes.htm

88delta88 · Joined: 09 Jun 2003 Posts: 2407 Location: Canada

Took a look at that site... Not sure I found the part of the website that describes the reason for rough idles.... Can you help me out? :-)