Operator

i got a "tune up" a long time ago, almost 3k miles ago, it included new air filter, new fuel filter, new copper spark plugs, new tranny fluid, belt retension after 3k on the new belts.

so now it runs rougher than i remember it and has been ever since august and i cant figure out what it would be? when i bring it back in 300 miles what should i tell my mechanic to look for? could the spark plug gaps be set wrong? maybe its supposed to be "rougher" and louder? it just seems to be more growly/raspy now than it used to be at all rpm except very high rpm where it still sings.

so besides my idle/dying problem which just started this week this roughness i noticed ever since day one back from the shop after the retension/tuneup so what could be the most common cause? or is this okay? it just feels like i have less hp or something.. <img src="confused.gif" border="0">

Operator

mystery to me too

Dave

You didn't mention if the tune up included plug wires, maybe you got a bad new one or an old one was damaged when the plugs were changed.

SidViscous

You could check the plug gaps too. Really screwed mine up, but more of a

vroooooooooooom--blubbaa blubba--Vroooooooommmm


Then again I need motor mounts bad so low end idle is not something I could notice if it was rough or not.

Robert D

Your car is a twin to mine in more ways than one! I too have an '88 944S in Stone Grey, WITH AN IDLE PROBLEM! I have been working through it seems everything...O2 sensor, replaced DME chip with stock chip, idle stabilizer, plugs, cap/rotor, new cams, top-end rbld. The idle is still rough, and the car wants to die when i let off the gas (drops to low RPM).
OH, it seems to be fine when it is cold though.
-Robert D.

Operator

no new wires... i didnt think it was part of 'routine maintenance' so i just got plugs.. copper plugs are the way to go right? maybe the S should use platinum 2 tip or something because of the high compression ratio? i wonder what the manual says...

Manning

Could be that in re-adjusting the belt the timing on the cams came off a bit and have caused the car to run rough, no? Did you bother to run the car back by the shop that worked on it? 3 months down the line they may not be willing to do anything about it.

Then again it could be incidental. In other words it could just be a fluke that your car started to run like poop after you got it back. We used to have folks come into the shop after we worked on this or that on their bike and claim that the flat tire they just got should be fixed for free because we had just worked on their bike.

Also, I wouldn't tell them what to look for, just tell them the symptoms and let them figure it out. When they tell you what they think post it and folks on the board can call bull**** or not. If you tell them what is wrong they will say "why yes it is" and fix it whether it was broken or not. Why? Because you as much as told them to.

tazman

One good test for spark plug wires is to look under the hood at night with the car running. You might get to see a nice light show! This will tell you if the insulation has broken down but unfortunately will not verify the ends are good.

sweanders

I believe that there is an extra fuse for 16-valve 944's DME, perhaps it is something that einfach?

Tabor

[quote]Originally posted by Robert DesRosier:
<strong>Your car is a twin to mine in more ways than one! I too have an '88 944S in Stone Grey, WITH AN IDLE PROBLEM! I have been working through it seems everything...O2 sensor, replaced DME chip with stock chip, idle stabilizer, plugs, cap/rotor, new cams, top-end rbld. The idle is still rough, and the car wants to die when i let off the gas (drops to low RPM).
OH, it seems to be fine when it is cold though.
-Robert D.</strong><hr></blockquote>

Your base line mixture may be the problem. Have a shop adjust it for you. This requires disconnecting the O2 sensor and adjusting the AFM (Air Flow Meter). It requires a CO sensor but only cost me 1 hour of labor and it fixed my idle problems (and emissions problems).

Also, check your temperature sensors.

Operator

would the cam timing being off affect performance -that- much? can cam timing be off that much before its detrimental to the engine? i mean i always thought the cams had to be set a certain way or the valves open up in all the wrong places and .. well .. we all know what happens when that happens.. right? i suppose theres a fine-tuning aspect to it?

Manning

Sure it will. And just think, you have two cams out of time. I don't recall just how much the cams can be advanced or retarded and not be in danger, maybe a few minutes of a degree. I also don't know if there is a whole hell of a lot you can do as far as fine tuning is concerned.

Again, I am not sure this is the cause. I also would like to reiterate that you should not tell the mechanic what to fix unless you know for 100% sure that is the problem. Just tell them the exact symptoms and let them sort it (as long as this is a trusted and reputable mechanic).