1993 Cutlass Supreme Convertible idling strange at higher RPMs

[True Blue]

Help! I am looking into buying a used 1993 Cutlass Supreme convertible with 117,000 miles on it. The owner just had the head gasket replaced, and complained to the dealer about idling problems at 3000 RPM. When the car is in park, and I floor it to higher RPM's, when above 3000 RPMs the engine idling fluctuates on its own without me pumping or letting off the gas as if there is something wrong and as if a hamster is stuck in the fuel injectors or something!!! The dealer replaced fuel filter, performed a very $$$ fuel induction service, and to no avail. What could be going wrong? The owner did say he has not tuned it up recently. My worry is something is wrong with compression, catalytic converter, etc. as it took the car quite sometime to accelerate but I just did not have time to check much during the test drive (the owner freaked out b/c I had it out for about an hour). Help, I need to make a decision on getting this beauty or run the other direction.

[RobertISaar]

that would be the park rev limiter... or at least it probaby is. that would explain not being able to get above that in park.

 

throw the shifter in 1st and see if it acts the same at WOT.

[willsboattail]

I had the same issue with my 1993 cutlass 3.4L convertible this spring. It is the rev limiter. Cuts out at exactly 3k RPMs. Nothing wrong.

[True Blue]

Thanks all for the responses on the strange idling at higher RPM's. Go figure, GM put something on a car to actually control high performance. This car also has what I consider a hard shift between 1st and 2nd gears under normal driving conditions (level ground, accelerations on the on-ramps at interstates, etc). Is this normal? The car is a beauty, it has some convertible top issues b/c of age, but can't complain for how it has held up and presents nicely.

[RobertISaar]

the rev limiter doesn't hinder performance at all. you should be limited to ~3K or so in park/neutral when not moving, and around 6200 while moving...

[tornado_735]

Rev limiter. Low ball the seller because of this "problem". If he bites, you'll get a nice car at a great price!

[True Blue]

So the hard shift in the transmission is normal? I drove a 94 convertible and compared to the 93, the 94 shifted like a dream. The 93 feels a little hard from 1st to 2nd, and so forth.

[True Blue]

Does the Rev limiter explain why the car will flutter every 2 or 3 seconds while flooring it at high RPM's in park??? The car also idles rough at just low RPM's but I attribute that to a much needed tune up.

[RobertISaar]

yeah, that'll do it... when it reaches the rev limit, it waits until it gets 50 or so RPM under the limit to kick back to life.

[94 olds vert]

^ what he said.

[willsboattail]

Thanks all for the responses on the strange idling at higher RPM's. Go figure, GM put something on a car to actually control high performance. This car also has what I consider a hard shift between 1st and 2nd gears under normal driving conditions (level ground, accelerations on the on-ramps at interstates, etc). Is this normal? The car is a beauty, it has some convertible top issues b/c of age, but can't complain for how it has held up and presents nicely.

 

:laugh: Same problem I also am having with my 93 Vert. See link to my previous thread on this question

http://www.w-body.com/showthread.php/42694-Tranny-Lurch

I have it scheduled for the transmission shop in two weeks!

[True Blue]

:laugh: Same problem I also am having with my 93 Vert. See link to my previous thread on this question

http://www.w-body.com/showthread.php/42694-Tranny-Lurch

I have it scheduled for the transmission shop in two weeks!

 

Thanks for the advise. Now, I need to make a decision on getting the car or not. Hard decision, I love how it looks but need to see if commitment to some minor fixes is worth my time. It will need a new top (urghhhh), possibly new (dual) exhaust, a good cleaning, and some engine degreasing. The dealer where the guy had the head gasket replaced left oil all over the place, and it is dirtying up the suspension, motor mounts, etc. I bet that modulator on the tranny will need replacing. Anyone know how much that will cost to replace the modulator?

[swift13]

i think its like 30 bucks give or take.

[Galaxie500XL]

The hard shift is a classic symptom of a vacuum modulator failure, or the vacuum hose is disconnected to the modulator. Without the vacuum modulator working properly, transmission line pressure stays at max, even during shifting, creating hard shifts.

 

I'll bet you find either a busted vacuum diaphram, or a disconnected modulator...explains both the high idle (vacuum leak), and also the hard shifting.

 

Be sure also to check the PCV, the hose kind of stinks on the 3.4, and it's easy to be running around with the PCV disconnected, since it sits kind of in a hole behind the intake, beside the power brake booster...

[Galaxie500XL]

Anyone know what happened, did the problem get figured out, or did he buy the car?

[True Blue]

All,

 

Sorry for being MIA the last week. Yes, I bought the 1993 convertible (see thread on 1993 Cutlass Supreme Convertible idling strange at higher RPMs). I will take delivery on July 28 and can't wait. I just got back from the Oldsmobile Club of America (OCA) nationals in Massachusetts. Needless to say, I am tired but wow, what a car show. Once I get the car, I am going to get a quote for a new top. The car needs some TLC, a new top, a tune up, tranny service, and hopefully wont be a money pit!!!! By the way, at the OCA show, there were 3 convertibles there, all very beautiful, clean, and a shame the drivers are not on this forum. They love their cars. I ran into a guy who reproduces the 1/4 window rubber strips that rot off these cars from the factory. He had a pair at the show and boy, they look great. A little pricy, but a source to go to if anyone needs those strips. If interested, let me know via this thread. And yes, I will post photos of this car once I get it tomorrow. The car currently has a black top, but I want to go with the brite white top. Anyone out there has a good lead on a place that has the correct vinyl, color, etc. for these cars? I have been reading the threads on the tops, but still a little unclear if anyone has had good or bad luck with any specific brand.