'88 325i runs rough. Any ideas? (video)

[Derptastic]

My 1988 325i runs rough in general and loses power when I hit the throttle, and it has been like this since I bought the car. My gas mileage is also 5-10mpg worse than my mother's E30 convertible (as reported by the analog gauge since my computer won't show me mpg). I checked the timing belt a while back and everything was aligned as it should be...

Also, after I kill the engine it has trouble starting back up again-I have to either crank it for 10 seconds until it sputters to life or wait 10 minutes before trying to start it again.

The engine also produces a whine after the throttle is first actuated (water pump maybe?)

Here is it's first startup of the day: http://youtu.be/Qp6yXOHHJjA

Any help in diagnosing the issue is appreciated.

[itskingsteelo]

my car (87 325e) has the same problem, as soon as it starts it shoots up to about 1100rpm then it drops to about 300 rpm and starts having trouble breathing. ive been told its my idle control valve. any other ideas?

[jlevie]

The most common cause of this is intake leaks. And to find them a smoke test is mandatory.

[itskingsteelo]

turns out i had a defective idle control valve, i replaced it and now its running smooth :)

[Derptastic]

I finally got around to building a DIY smoke machine and performing a test. I found a few cracked hoses that were leaking, and I discovered a large leak around the aft blind plugs. I suspect this might be the cause of my problems. I'm ordering a head cover gasket and new set of blind plugs so I can install them next week... keeping my fingers crossed...

Any recommendations on a gasket/plug kit?

[jlevie]

Quite possibly the best valve cover gasket is the VR part. I get the rubber bungs a dozen at a time from my dealer as they, and the gasket, need to be replaced every time the valves are adjusted (every 10K).

[Derptastic]

Got the parts today. When installing the plugs should I wet around where it contacts the head?

[Derptastic]

I figured it out (installed dry with some gasket maker)... After installing new seal plugs and a new gasket, and a new crankcase vent hose my car idles better, but I still have throttle hesitation.

For good measure I checked my TPS and inspected the carbon track on my AFM. Both checked out fine.

Also, what is that noise that starts 19 seconds into the video?

[jlevie]

Unless it duplicates what a commercial smoke machine does (long persistence oil smoke and pressure control) and unless you plug the exhaust, replace the AFM with a plugs & nipple for smoke introduction, and hold a smoke pressure of 2-4psi for at least 5 minutes, you may not find all the leaks.

[Derptastic]

Last week I had a proper smoke test done which revealed a leak at one of the intake manifold gaskets. I replaced them all and buttoned everything back together...

The car will start and initially idle fine, and the hesitation is gone, but after a minute or so it starts to run very rough.

New video: http://youtu.be/2HwYFQAfDWY

Any thoughts?

[dnguyen1963]

Have you done the smoke test post installation? The car idles above 1K (should be around 750 rpm) and it sounds like you have not fixed all the leaks.

[Derptastic]

I have not performed another smoke test. I should also double check the tightness of the manifold nuts...

[Derptastic]

I went back and checked the nuts and several were loose... I tightened everything up, reassembled...

Now my poor idle and hesitation are back... i guess another smoke test is in order

[jd_e30]

Idles high. Did you check throttle cable tension? Smoke test it. Any oil on spark plugs? When was the last valve adjustment?