88 325 Is Help

Zdaneman · Dec 24, 2005

Gents,

Just purchased a really clean 88 325is with 88k miles. It has been running great! On the last road trip it was getting 36.5 MPG at 70 MPH. I really like the car. I have put on new wheels and tires and basic clean up work detailing it out.

However, now I have a problem. The car is hard to strart sometimes and once it warms up it starts to idle rough. It will start around 650 RPM and then surge to 2K and stick. Then it falls back down? This will start idleing rough and then stop a few miles or minutes later. I have taken the car to a very experienced local mechanic and he has replaced the oxygen sensor, new plugs, and ran a few tests...not sure. However, I've got 1K invested now and still the car does not run correctly.

Any suggestions? Besides sale it!!

[driving2]

epj3 · Dec 24, 2005

Sounds like bad ECU, bad fuel pressure regulator, vacuume leak, or bad crank positon sensor. Could also be a bad idle control valve but you can go without that and it'll still idle semi-okay.

ldzpstnr · Dec 24, 2005

There is a little Idle control computer and Idle control valve that could be the problem. The Idle valve is located on the top of the intake manifold connected to two rubber hoses. The idle computer is hidden up above the ECU in teh glove box. When one goes out, the other usually does to. One way to check them is to remove the Idle contrl valve and plug the holes. The car wont idle unless you hold open the throttle a little bit. But it should not do any surging then.

Just things to check. I had trouble with my idle control valve and module before, and it was acting the same as your car.

jrt67ss350 · Dec 24, 2005

ldzpstnr said:

Except in a 325i, the idle control valve is NOT on top of the intake manifold - it is mounted to the intake boot between the air flow meter and the throttle body. It's different than an eta engine.

I'd put my money on the fuel pressure regulator at this point. There's a vacuum line that runs from the passenger side of the intake manifold up to the fuel pressure regulator which is the little canister looking thing mounted to the front of the fuel rail. There's a rubber diaphragm in that canister, and over time they crack and stop working. You can quickly and unscientifically test the fuel pressure regulator by disconnecting the vacuum line from the intake manifold and sucking on it. You should be able to suck a small amount of air out before you can't suck any more. If you can just keep sucking more and more air out and it never builds up a vacuum, then the fuel pressure regulator is shot.

One thing you can do to see if the idle air control motor is even working is to disconnect the electrical connector from it and see if the engine's behavior changes. If it doesn't, then the idle air control motor and/or idle computer may be bad.

epj3 · Dec 24, 2005

ldzpstnr said:

There is a little Idle control computer and Idle control valve that could be the problem. The Idle valve is located on the top of the intake manifold connected to two rubber hoses. The idle computer is hidden up above the ECU in teh glove box. When one goes out, the other usually does to. One way to check them is to remove the Idle contrl valve and plug the holes. The car wont idle unless you hold open the throttle a little bit. But it should not do any surging then.

Just things to check. I had trouble with my idle control valve and module before, and it was acting the same as your car.

"I" engines do NOT have an "idle computer" - that is only ETA's. Along with cold start injectors, that's ETA's only, too.

jrt67ss350 · Dec 24, 2005

epj3 said:

Interesting - I did not realize that.

epj3 · Dec 24, 2005

jrt67ss350 said:

Yep, controlled via ECU. "ETA" motors (I think motronic 1.0, and early 1.3's in the m30) is the last EFI system to have a separate idle system, last to have crank position sensors in the bellhousing instead of at the front, and the last to have any type of cold start injector.

Zdaneman · Dec 25, 2005

Gents,

Thanks for all the info! I'm waiting on my repair manual before I dive into trying to fix this thing myself!

Merry Christmas and thanks for the assistance. [driving]

Zdanemen sends

JimHow · Dec 26, 2005

I would recommend taking the intake boot off, and spraying the ICV and throttle with a good throttle body cleaner before all else. My idle problems disappeared after doing this.

Zdaneman · Dec 27, 2005

OK,

I'll try them all. Noticed today driving to work with the little red monster the check engine light is coming on too. Oil was just changed that less than two weeks ago, so i know there is no danger to the engine. Must be the ECU? Would the ECU, fuel regulator, or idle control valve make the check engine flash too. It goes out above 30 to 35 mph and runs fine. I have notice a loss in gas miliage of about 6-8 miles to the gallon. I'd be interested in everyones thoughts!

I love this site, so glad I found it! Once I get this licked I'll let everyone know who was right! Thanks again!

Zdaneman sends [duh]

nadroj · Dec 27, 2005

wow thats really bad gas milage i would check the o2 sensor. my 318iS idled bad when it had a bad o2 sensor and the check engine light would come on at idle and it went off after i drove a lil.

Zdaneman · Dec 29, 2005

Idle Control Valve

Well all,

Got the shop manual today in the mail. Did some trouble shooting and it looks like its the Idle control valve! I will put the new one in once it arrives. If it doesn't do the trick, the ECU is next. The fuel regulator checks out...plenty of vacume. Did the test on a cold and hot loop with the car. Pretty simple stuff!

Oh, its got a brand new o2 sensor! That cost me 469.00 bucks! Why is it all stealerships are the same...Ducati, Kawasaki, BMW. Thank God, my buddy owns a Kawasaki shop or I wouldn't be racing my ELR 99 ZRX 1100!

I sold the Ducati..900SS due to high parts cost and I turned all the wrenches!

Again, thanks to all! I'll keep you posted on my success! I love this site! [clap]

Zdaneman sends [driving2]

Zdaneman · Jan 4, 2006

Saga Continues

Well I replaced the Idle control valve today! No change, it is still surging. Fuel regulator checks out but I just going to replace both the fuel regulator and the ECU. Is there anything else that could be causing the problem? [pray]

Thanks for all your input!

Zdaneman sends [unsure]

epj3 · Jan 4, 2006

Zdaneman said:

You paid $469.00 for a $60 o2 sensor?!?!?!?!?!? Holy shit!!!!!! M20 is the easiest O2 sensor to get to on ANY car i have ever seen (don't even need a special tool) and the sensor is $60!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Dude you got ripped off up the butt! Holy shit, I sold my entire E30 shell, very good engine, and drivetrain for $500.

Cecil · Jan 4, 2006

I had a similar problem when my Electronic box was soaked in water after a heavy downpour tried swapping with a similar one see what happens.

Zdaneman · Jan 5, 2006

Cecil,

The ECU is next after the Fuel Regulator. Today I replaced the Alternator after it sucked the battery dead. Another 100.00! This 3000.00 car is now at the 1300.00 parts and service in addition to the purchase price level. I'm doing my own work now, no more shop rip offs! Well, I guess by the time I get done. it will be in really good sahpe and I'll just hang on to it!

By the way fellows, BWM in Fairfax, VA charges 105.00 dollars an hour for service! Ain't that sweet! [doorpeek]

Zdaneman sends [:(]

epj3 · Jan 5, 2006

Zdaneman said:

Never take your older car to a dealer!!! Besides the cost of labor and the HORRIBLE cost on parts - an independent mechanic specializing in european cars will do much better work. The dealer has business no matter what - as long as that dealer is selling cars with a warranty, their repair shop makes money. An independent mechanic has a reputation to uphold, and will be much much cheaper - usually selling parts for a lot less than the dealer.

If you ever need any advice, be sure to ask here. Between me, justin, chesty, and a few others - you'll more than likely get a very good answer about repairs. I'm also positive we could save you tons of money as all of us are experienced in saving money when it comes to repairs. [:p]

jrt67ss350 · Jan 5, 2006

epj3 said:

I second that. There are a few of us around here that are pretty knowledgeable with these cars, and we are very happy to share what we know. We do our own work on these cars and are pros at saving money with repairs when we can.

ldzpstnr · Jan 6, 2006

I third that. Jrt, Epj3, and b-daddy have helped me before. I think this is the best E30 board around.

Hey JRT. You truly have one of the best chevys ever made. The '67 camaro ss350 and the '65 corvette grand sport are the best chevys' ever made. I think its the corvette grand sport, its the one that was blue with white racing stripes. It was made to race with the shelby corbras, but I think they maybe only made 10 of them???? I am not a chevy guy, could be wrong. Later

Aaron

epj3 · Jan 6, 2006

ldzpstnr said:

Well, there are quite a few e30 forums around that are literally dedicated to e30's. But the problem is searching and finding the information you need is hectic. Fortunately (I think...) justin, me, bigdaddy, and a few others have collectively replaced everything on an e30.

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