E30 experts, need advice

I seem to have an intermittant problem with my E30 that i have thoughts on what it might be and wanted a sounding board for it.

1986 325e automatic 179k miles. PO (someone from this board) installed a reported Ebay chip on the motor.

intermittant problem that manifests by it running like its corked. Full throttle barely accelerates and sudden throttle dips cause some popping (backfire?) in the exhaust. It only pops up on occasion (last night was the second major occurrence, it happened bigtime the other year as well. its happened small and promptly dissappeared a few times in between)

I know it will occur when i start the car up and instead of the SI board reading "oilchange" ir reads "inspection" I am ASSumeing that this means that there is a code. Problem is that the lights on the left of the "oilchange/insection" lights on the dash dont light up on startup (i know i need to troubleshoot these at some point, spring break is in a week and i plan to mess with that then) so im guessing that the check engine light that is supposed to blink mentioned in this writeup http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm is one of my non-working lights.

car has also experienced flat spots and hangups in acceleration on a fairly regular basis. I recently had a new exhaust put on the car and changed O2 sensor/plugs/wires on it. (plugs are basic plugs, not platinums)

another issue is that I can hear the RPMs of the engine in the sterio. I am guessing that since i did the plug wires and havent seemingly had charging problems that this is an indication that the engine ground needs to be replaced/upgraded.

does this read to you like a failing transfer pump? what else might you think it would be?(I really want to be able to fix it right the first time)

Check grounds, fuel pump, AFM, and see if you can get a factory chip.

That's where I would start.

Disconnect the OX sensor. it will put it in loopback mode . See if the problem goes away.

Also have you done a cap and rotor?

I also agree with getting a stock ecu to test. also the crank sensor can cause similar symptoms

B

I havent done the cap and rotor, ill add removal of them and inspection to the list of to-do over break.

I hate intermittent problems like this

Pull the ECM out from behind the glove box. Mine had the same issue. (except I don't recall a whining in the stereo) When I pulled the ECM connector out, all the plating had come off the pins and was like zinc confetti in the connector. Dumped the confetti, blasted it out with some air, dusted it off with a paintbrush, re-installed, problem solved... until my FPR died the next week :)

check the intake hose for cracks, particularly the elbow after the afm. the car will run like crap (no power, then sudden surges, etc) if there's a leak. if there's a crack, duck tape will get you going again until you can get the part from the dealer/intarweb.

That's not a transfer pump symptom, if it helps narrow things down.

well, it did it again this morning leading me to borrowing the exploder to get to class (late)

at least its no longer intermittant i guess?

idles fine, accelerates just off ilde fine, any more then that and it just dosent accelerate.

not a transfer pump symptom, eh? ill have to tear into it next week and check the electricals with the ECM, redo the ground, inspect the cap and rotor.

ill check the boot again, but have in the past and it looked fine in the crevices.

Clogged cat?

unlikely to have started out intermittent. relay for main fuel pump?

dj06482 wrote: Clogged cat?

brand new

im not really gonna get to dig into the car until friday at the earliest.

even then i need to address the E36 M3list on the exploder first (CEL, windshield washers not working, in depth cleaning and perhaps some rust prevension, oilchange)

however please keep the ideas coming! i hadn't thought of the connector for the ECM or the relay. It is helping make the testing list inclusive so if its something cheap/free i wont be throwing money at a dumb problem.

Finally got around to tearing into the car for diagnosis. (college and free time are not cohesive )

removed the ground strap and cleaned the contacts and checked it over, no change

removed the ECM, contacts look good, cleaned anyways, no change

removed dizzy, cleaned minor carbon scoring, put back on, no change..

remove back seat, remove wires to transfer pump.. no change.. the plot thickens! check voltage to pump, 12-13 volts.. so its getting power.. its just a bum pump...

anyone know a magic cheap source for a transfer pump, or is rockauto's $150 the best ill see? (pelican and bavauto are closer to $200)

I dunno. I've only had to fix ones that only had the one pump in the tank, and I just bolted in a generic walbro 190 or whatever.

Just a note: inspection doesn't have anything to do with a code. You were supposed to take it to the dealer every xxx miles for an "inspection". Then the dealer would give you a laundry list of things wrong.

I don't know if it holds true for E30s (though given the way BMW does things, I wouldn't doubt that it does), but the transfer pumps in the E28s can be directly replaced with one from a Chevy Vega. You have to mount it in the assembly, but that's easy, and it only cost about 40 when I did mine way back when. Worth a look, perhaps.

The SI board probably needs a new battery. The display will start flashing random combinations like that when the battery goes bad. As far as the intermittent engine operation, I'd take a look at that eBay chip...they don't have a very good track record. See if you can borrow a stock ECU from someone and swap it in for a while to see if there's any change. In my experience, the fuel pump works or it doesn't.

stuart in mn wrote: See if you can borrow a stock ECU from someone and swap it in for a while to see if there's any change. In my experience, the fuel pump works or it doesn't.

BTW, I have what should be one (check numbers)

Did anybody mention fuel pressure regulator?

The RPM being heard through the radio may well be a ground wire on the alternator broken or corroded...

I think the best plan of attack is to address this first

"remove back seat, remove wires to transfer pump.. no change.. the plot thickens! check voltage to pump, 12-13 volts.. so its getting power.. its just a bum pump... "

and then regroup and see if there are more problems.

(money thrown at this reduces my autocross budget)

hmm, could this be the problem?

had to fish for the strainer and impeller.

the motor does NOT spin when plugged in, ordering replacement from rock auto..

UPDATE!

new transfer pump in small change for the better, but not fixed.

found vacuum leak leading the the idle air control, new hose solved (still not running right)

took apart the whole intake tract up to the throttle body and checked the flapper door. nothing further there but another conundrum. Oil in the intake boot seeming to be coming from the Idle air control. there was a small puddle in the rubber intake boot.

jiggled the wire leading to the IAC and it is now wanting to idle at 1800rpm.

need to get the volt/ammeter from the other house and test the IAC and voltage leading to it.

but i am confused as hell where the oil came from.

the oil comes from the valve cover breather. Quite normal actually.

You also can test the Idle stabilizer by using a jumper wire to run a new ground. Usually it looses ground off the engine. See if a new ground will get the idle where it needs to be.

Could the IAC be gummed up? That seems to be a common problem on a lot of older cars.