Author Topic: Running rough, lack of power (Read 3312 times)

RIPDOTCOM · « **on:** December 11, 2007, 10:50:58 AM »

I thought I had this car right but its time for some help. It is a 91 318IS and it runs rough exactly as a car would with an aggrssive cam in it. Engine noise up front (sounds like the timing chain tensioner needs to be replaced) The car just doesnt run right and it feels like the timing is not advancing correctly under load. I also have a perfect running 91 318 that I have swapped the following from to troubleshoot it.

Swapped IAC (helped the hunting idle but still real choppy but stays around 800 without moving)
Swapped coolant temp sensor (I know thise wreaked havoc on M20's from experience) no change
Swapped the cam PS and the Crank PS with no noticable change
Swapped AFM's no change.

As for maintenance I did the following

New Fuel pump and filter
Pulled fuel rail and manually cleaned injectors
Installed new NGK dual plugs.
flushed engine put in new mobil 1 synthetic
Removed cat, running 2.5" straight to a dynomax Muffler

All cylinders are firing and I am pretty confident that all injectors are firing.

I have had the car for a few weeks and it simply has never run right. I am wondering if the pervious owner attempted a timing chain replacement and put it on wrong. How can i tell if the timing is correct?

Any other recommendations would be greatly appreciated.

tjts1 · « **Reply #1 on:** December 11, 2007, 11:06:33 AM »

Check for vacuum leaks under the intake.
http://www.m42club.com/forums/showthread.php?t=2742

RIPDOTCOM · « **Reply #2 on:** December 11, 2007, 01:50:30 PM »

Checked with an unlit propane torch and rerouted all vacuum lines when doing a heater plate delete.

Febi Guibo · « **Reply #3 on:** December 11, 2007, 04:26:37 PM »

I'm assuming no oil leaks anywhere... maybe cams not aligned to TDC?

RIPDOTCOM · « **Reply #4 on:** December 11, 2007, 07:01:33 PM »

Quote from: Febi Guibo;39288

I'm assuming no oil leaks anywhere... maybe cams not aligned to TDC?

Possibly, How can I tell if they are in the proper position? Would I have to pull the whole timing chain covers off or can I adjust by removing the tensioner?

Jtuner · « **Reply #5 on:** December 11, 2007, 07:58:10 PM »

I just did the chain guide rails,, you should be able to just pull off your valve cover to see the cam gears.. they have little arrows on them that should be in identical position (i.e. both pointing up).. I think up is TDC if I'm not mistaken, but if you have one arrow at 12 o clock, and one at 2 o clock, I would think there may be something wrong.. not to mention much more than a tooth difference, the piston will smack the valve

good luck, and let us know what we can do to help and how you make out with it!

Jtuner · « **Reply #6 on:** December 11, 2007, 07:58:46 PM »

are our cam gears keyed?

nicknikolovski · « **Reply #7 on:** December 12, 2007, 02:02:32 AM »

Running rough could be ignition coils, is the check engine light on?

Coils are very common for cars running crap, is the car misfiring at all?

Also check your oxygen sensor.