BruceA

Hi. My car has seen much work this past year and the list of maintenance, service and repairs (from new Tbelt, to new motor mounts, to new upper and lower rad hoses, to p/s hoses etc. etc.) has been long in getting it up to a very fine running and looking specimen...it is trying hard to beat me in the process but I have NOT surrendered.. okay the new issue: on acceleration there is hesitancy and vibration.. we thought maybe carbon deposits, also checked compression and one was low but the others were all fine; so injection cleaning was done and it seemed to improve; we also checked out for any leaks etc, and installed a couple new air hoses. But the problem continues, I'd love a list of things that I should be checking. Thank you. B.

MikeN

Sounds like you may have some sort of ignition problem.......plug wires bad/crossed, coil(s) bad, dist. caps/rotors bad, spark plugs bad/fouled........just some thoughts......

BruceA

Hi Mike, The timing belt, timing belt idler, Spark plugs, distributor caps and rotors were all replaced in January 2003 B.

MikeN

Did these issues start right after the above was changed? Happening before these changes? Just cropped up??

Niels Jørgensen

When it comes to poor acceleration, and all the easy things have been checked and dealt with, the finger tends to end up pointing in the general direction of the MAF.

Try getting one from another car or simply have John Speake test it for you.

BruceA

Hi Mike, No it didn't start until this July and never occured prior to. I had thought one possibility was the car had a small accident (hit up at the very front on passenger side - between front wheel and bumper) and it then sat for a month or so until repaired; I thought that might have been an issue (i.e., sitting) but...

Neils, Whose John Speake?

MikeN

Hmmmm, I'd run through the above including the MAF once again. A bad MAF will definitely make the car sluggish and run rough.......is this what you may be calling a vibration?

John Speake

Bruce, Mike,
I can provide refurbished MAF. See my web site, shown with my signature, below.

My agent in the USA has a MAF in stock, which can be sent to you on a "buy or return" basis Then you can really check if the MAF is an issue for your car.

If your '88 car does not have cats fitted, then MAF ageing is a strong possibility for weak running/hesistation. The only other thing you might have is some partially blocked injectors.

BruceA

I'll put the MAF on my list. As to vibration, it is more than the engine being a little rough... the best way to describe it is when I drive the car, as I accelerate (at any speed.. so from stop position to start acceleration or even if say I coast at 30mph and then accelerate..) the acceleration is very sluggish (if I had a standard I'd say it felt like I wasn't pressing the pedal enough)... I do notice the symtoms are less noticable when I do a hard acceleration (after the first few seconds)... also i believe (I'll have to test more) than once the car has been driving for some time the systems seems to be a little less... I'm taking it in to be looked at tomorrow

John Pirtle

Bad vacuum leak?

One way to test is to seal off the MAF with a baggy and strong rubber bands. Then disconnect one of the larger vacuum hoses to the intake and blow in it. Listen.

The workshop manuals actually show a cap for the MAF with an air valve stem, and you pump it up. Some owners have bought a large bicycle inner tube, cut it to fit....

Be sure to remove the rotors and inspect them. More than a couple of new ones have been cracked!

John Pirtle
87 a/t 149.7k
http://members.rennlist.com/pirtle

Tommy928

Have you checked the coils? They have a tendency of going bad resulting in vibration and sluggishness. My coils went bad on my 87' and they almost caused a fire from unburned fuel in the cats.

GlenL

Start simple: wires and plugs. A misfire will do what you describe. Could be a loose connection at one of the wire ends.

jpitman2

Sounds like misfire to me. If you have mechanical advance in dizzy, and its frozen, or not moving easily, can also do this.
jp 83 S

elemental

yeah HT leads - does your 88 s4 have very 'bent' wires leading round to the front plug on each bank? I've just seen a 88 with that, and the wire was arcing like a tropical storm. I don't know for sure but I was told that these were changed on a recall basis here in Europe. Worth checking anyway, before you go down the MAF route.

Erik - Denmark

Bruce,
What did you do with the missing compression on the one cylinder?