3.2 running poorly

88911coupe · 01-05-2007, 12:56 PM

OK, I've been searching and reading threads but none seem to address my speific problem. First the basics, '88 3.2, totally stock, 160k, in need of valve guides. I recently ran a can of Sea Foam through it and it "seems" the problem has gotten a little worse but it's been there for some time. Here's the symptoms: when cold it starts/idles fine but off the line and accelerating through lower rpms runs rough, almost a fluttering acceleration for lack of a better term. It gets better as it warms up but does not seem to go away. I'm trying to figure out where to start. BTW, just put new plugs in last week since old ones were fouled (2,3,5,6 were by far worst). I was thinking the sensor track on the AFM but wouldn't it affect it whether cold or warm?
Also, it's overdue for a valve adjustment and they are getting loud but my mechanic who's been wrenching 911s for decades suggested leaving them a little loose since we will be doing the top end shortly. Could loose valves cause this? Any suggestions on where to start appreciated.
Leaking o ring on injectors?
leaking intake?
TIA

Zeke · 01:15 PM

I have an '88 coupe and I've been bookmarking threads as they pop up regarding the various problems and the cures. You've got a couple of ideas there that come up, but also the head temperature sensor and the flywheel sensors should be tested according to the threads. An upgrade is available for the head temp sensor. I'd get the Bentley out and start with the digital meter on that sensor and then the rest.

Make sure the intake is clean. Spray carb cleaner or WD 40 on the intake runners and injectors while the engine is running. always keep a fire extinguisher on hand. That's all I can do for you until some more informed folks arrive.

Edit: Listen to me. I'm giving advice on tuning a type of car I've had for only 3 months!!

88911coupe · 01-06-2007, 05:34 AM

Bump for saturday am crowd. Also, what is the safest way to check for intake leaks...is a propane torch safe or am I going to blow something up?

jbrinkley · 01-06-2007, 05:46 AM

cht like milt said. It wouldn't start if flywheel sensors were bad.
use gas for intake leak check, unplug O2 sensor and idle control valve and then use the gas.
change dme relay and see if you can swap AFm's with a friend, also try swap of dme box with a friend.

but first check your plugs again and make sure your wires are on tight and fully connected since you changed those first and then started having problems.
your mix could be off also.
if when you unplug O2 sensor and idle control valve you notice a drastic rpm change then your mix is almost certainly out of wack
but like they say..... whatever you messed with last is probably the easiest culprit, and should be checked first

88911coupe · 01-06-2007, 06:06 AM

Pardon a possibly dumb question but what is the reason behind disconnecting the O2 sensor and ICV before I check for leaks? I just checked the plugs as well and they seemed to be tight but I will be driving this am and I'll find out. I'm going to look at the AFM's contact track as soon as I can figure out how to dissasemble it...there don't appear to be ANY bolts or nuts to loosen.
Thanks for the reply,

gtu935 · gtu935's Garage

Check out the cyl head temp sensor.

jbrinkley · 01-06-2007, 06:46 AM

quick answer.. o2 and icv work together to control idle speed and mix (within range) They're working now together with any leaks you have. sending propane or map into it will kick them in gear and adjust accordingly (within limits)
but like they said CHT first, they don't neccesarily fail at once.
you have to pry off the bottom plastic cover on the afm to look at it

stlrj · 01-06-2007, 08:00 AM

160k...does that mean orginal ignition wires?

88911coupe · 01-06-2007, 10:36 AM

Plug wires, cap and rotor all changed 4/01. Cyl Head sensor replaced 6/02. I'll look at the AFM as well...hopefully I can get it back on after I pry it off...just some sort of sealant to put it back on?
Thanks for the suggestions.

chris57 · 01-06-2007, 12:26 PM

Small amount of clear/black silicone will do the trick.

stlrj · 01-07-2007, 09:04 AM

I use a strip caulk from 3M. That way you can open it up again and it still gives an air tight seal.

88911coupe · 01-07-2007, 09:13 AM

Is there any specifc type of cauld from 3M you recommend?

PatrickB · PatrickB's Garage

Hey Buck~

I had to jump in with my $.02, as you'll likely see my name pop up in your search... It certainly couldn't hurt to replace 6 year old plug wires, cap & rotor, especially if your car has experienced the last couple of Texas summers! In the end, my problems were linked to 2 bad fuel injectors. My car with new injectors ran smoother and stronger with 135k miles on it, then it did with 60k when I bought it. I've got 152k on it now, and still runs strong as ever! As everyone has added valuable possible problems, don't discount any of it!! Another possible item to check, is the DME Unit itself. Sometimes they develop microscopic cracks on solder joints that wreak havic similar to what you are experiencing. If at all possible, find another good running 3.2 in your area, and try swapping parts with yours. It's what I did, and it saved me from replacing parts that were working. Good luck!!

88911coupe · 01-08-2007, 05:49 AM

Patrick, thanks for the suggestions...it's possible that when I was changing the plugs I somehow may have damaged a plug wire or two. I also bought new injector seals and plan to spray some carb cleaner down there to see if I have air leaks. I was trying to use my propane to find leaks but could not get anything to happen. I was nervous about how much propane to spray for fear of damaging something so I may not have been allowing enough out.
I'll also see if I can find another DME to swap to see if I can narrow it down.