E30 2.5 running terrible

jakepressley · **Posted:** Sat Jan 01, 2011 4:50 pm

I've been through the wringer with this thing...

It only runs when I feather the throttle, and then it just barley sounds like 6 cylinders are firing. I can increase the frequency of the feathering to up my RMP's to only seems to be running when I let my foot off the gas... if that makes any sense at all.

I've done some work on the fuel system-(fuel pump, new lines and a filter) changed plugs, wires and cap.

I'm thinking a it might be a vacume line leaking.... but its got to be huge..

Possibly an Intake Manifold Gasket??

One last detail.... The check engine light within the gauge cluster is blinking....I think this car has two check engine lights, the other is lower and not part of the cluster.... When I check for codes I get a "no error" code back. The cluster IS out of another car if that matters, although the original one (burned and all) blinked as well.

Any help would be most appreciated.

Getting this running is my NY Resolution...

:lol:

JamesMilko · **Posted:** Sat Jan 01, 2011 5:22 pm

Blinking CEL in most cars is used to indicate a misfire condition. I'm not terribly familiar with e30s though.

How does it run with your foot on the floor? If it's a vacuum issue it should even out at open throttle since there is no vacuum. Is it running super rich when it does run? Do you have a vacuum gauge you could use to check your idle vacuum?

jakepressley · **Posted:** Sat Jan 01, 2011 5:33 pm

to the floor... car stalls..

I have to work the throttle to keep it running... It won't idol on its own.

super rich... nope it actually sounds lean and is misfiring pretty badly.

jakepressley · **Posted:** Sat Jan 01, 2011 6:19 pm

I stand corrected... I just went outside and held it WOT... the car cycled to the redline then came down... sounded like it would stall....but didn't.... then went right back up to the redline again.

its got to be leaking somewhere around the intake...

JohnByers · **Posted:** Sat Jan 01, 2011 6:26 pm

This may sound super simple and you may have checked it. On mine it did something similar and it was the actual intake boot going to the TB, on the bottom on the accordion it had a split deep in the fold that from the naked eye appeared to be in great shape. New intake boot and all was fixed.

GL

BretLuter · **Posted:** Sat Jan 01, 2011 7:23 pm

intake mani gaskets don't just wear out on those things, the only time I've seen a massive leak on an intake mani gasket is when a friend of mine replaced the head gasket + intake mani gaskets, he pulled the intake and replace all of the gaskets, but didn't realize that 2 of the old intake mani gaskets were stuck to the intake when he put it back together- thus creating a huge gap on the runners that had only 1 gasket.

I'd also suggest checking the intake rubber boot, it can crack and create a huge leak that's hard to see because it opens up when the boot flexes.

What's the history on the running problem?? What work did you do or parts did you replace? Was it running better or worse any time recently??

jakepressley · **Posted:** Sun Jan 02, 2011 12:42 am

I'll check the TB boot, it looks original... I ran my hand around the thing to feel for a crack or dry rot and nothing felt wrong. I'll take it off and get a better look.

The history on this car gets sketcher as I go. I originally purchased the car for a little more than a lemons rig would have to cost to fix and flip. The previous owner (friend of a friend) wasn't too wicked honest about a few items once I started digging. In short I've never heard the thing run 100%....

Thing is... I really like this little car and probably won't sell it if I can get it sorted. I see how much fun people have with these at the track... I may look into spec in a few... dozen or so years....

I've done very little to this point but am getting ready for the bigger priced items... timing belt, head bolts, valve lash, waterpump.. and want to hear the motor run a little better than it currently is.

I'm in this far:
New Control Arms, radiator, fuel pump, fuel lines, fuel filter, plugs, wires, cap, rotor, brakes other odds and ends

Aaron Buckley · **Posted:** Sun Jan 02, 2011 1:06 am

Jake, have someone sit in the car and try to keep the car running while spraying starting fluid around the the throttle body boot. If you it instantly picks up in rpms, you likely found your problem. - AB

KendtEklund · **Joined:** Tue Mar 27, 2007 7:29 pm **Posts:** 1204

One thing that came up talking to a BMW mechanic at the LeMons race this weekend was the MAF - he explained the BMW MAF is a flapper door that can easily start binding. He said to look inside the MAF and see if there is any scoring showing that the flapper is hitting the inside of the MAF. He also mentioned bad grounds on the injector rail as a common issue.
Edit - fuel pressure regulator another common failure.

jakepressley · **Posted:** Sun Jan 02, 2011 9:31 am

Thanks All!!!

I've got some work to do today!!

I've looked inside the stock air box and the flapper seems to still have some spring to it. But I'll check for the scoring.

Great thinking about the fuel rail.. I was thinking of pulling the intake to get a look at the injectors, so I'll add that to the list.

Fuel Pressure Regulator...
I pulled the main feed to the fuel line and blew air back through the tank and blew the crappy gas out of the fuel rail... would this tell me anything about the fuel pressure regulator. Our chump car (Audi) has a fuel distributor, which we freed up dong the same blowing air in both ends (tank and rail) to unbooger it.

Bernie Baake · **Posted:** Sun Jan 02, 2011 11:30 am

Blowing through the pressure regulator won't do anything except clear a plugged line. you need to put a pressure gauge on the main feed line and see what press is being fed to the injectors.This is how I found the prob on the 86 vette race car.
Looking at the maf is only half of the proceedure you need to find out what the resistance range of the maf is, and move the flapper through out it's entire range of travel and insure the change as you move the flapper is linear, same goes for the TPS. Get a good multimeter for this.
Do you have a manual for the car?If not buy or borrow one. It sounds like your using the wild assed guess method of finding this prob. the shop manual will give you proceedures to isolate the trouble. This will allow you to make a scientific wild assed guess.

jakepressley · **Posted:** Sun Jan 02, 2011 12:41 pm

The fuel injectors were hard wired in... I guess there was a connection there that's bad about failing. It was cut out and wired up directly... Its ugly as hell so I'm going to clean that up. Wondering if the injectors could be sending bad info to idol/tps???

intake boot is fine...

Intake Manifold gaskets are fine

JohnByers · **Posted:** Sun Jan 02, 2011 3:00 pm

I have a .pdf of the Bentley manual if you need a copy of it. Would need to figure out where to host it, but I have a copy.

Steven Carter · **Posted:** Sun Jan 02, 2011 3:21 pm

jakepressley wrote:

The fuel injectors were hard wired in... I guess there was a connection there that's bad about failing. It was cut out and wired up directly... Its ugly as hell so I'm going to clean that up. Wondering if the injectors could be sending bad info to idol/tps???

That's where I'd start.

edit: put a mechanic's stethoscope or long-stemmed screwdriver on each injector while the car is running and listen for the crisp clickety noise of the injectors opening and closing. (Put your ear on the screwdriver handle if you go that route) They could be clogged, but it will at least confirm the signal is getting there.

Then look over the Idle Control Valve and make sure it's functioning correctly (You need a Bentley's manual... I have some additional stuff in .pdf that may help as well.)

+1 on the FPR.

Hard to tell much more until we get more info.

BTW Kendt, E30 uses AirFlow Metering, not Mass Air Flow sensors like the later models do.. MAF conversions can be done (cf Miller Performance), and have some nice improvements for those willing to tinker with fuel maps and such. Figured you mis-typed since you described an AFM, but it can make matters confusing.

Good luck

edit: just checked your profile...if you could PM me your email, I'll send that stuff to you.

BretLuter · **Posted:** Sun Jan 02, 2011 3:53 pm

A couple of random things:

Idle control valve dead or dying is not going to cause the problems you describe, so I'd leave it alone for now.

TPS is not likely the culprit either, since it basically tells the ECU when the throttle is fully closed or fully open- not really any different signal for all those positions in between.

How the hell did they hardwire the injectors?? like solder wires to the terminals hard wired???? GAH!!! Sounds like you might need to replace the injector wiring harness??? I can help you if you need one.

Is the fuel tank/fuel pump all gunked up?

I agree with Bernie that while the WAG diagnosis method does sometimes work, it's usually just an exercise in frustration. You really need to start checking things off as OK, Bad or questionable. Then go back through the list and work on the bad things, then the questionable things to see what you come up with.

The E30 Bentley manual has some good troubleshooting specs- like resistance values for checking the AFM, etc that can be done with basic diagnostic tools like a multi meter. Fuel pressure may really be telling you something here too, but most people don't have a proper fuel pressure gauge that will work on this car- and a decent one is probably $75-100.

How about basics like compression on all cylinders?? Maybe a broken timing belt sometime in the cars past that the PO "fixed" by sticking a new timing belt on without repairing the bent valve(s)??? Probably not likely, but I've seen crazy stuff like this before.

One piece of advice that you really should heed- change the timing belt sooner rather than later. I understand you don't want to throw good money after bad, but if the timing belt breaks, you'll really be in a pickle and just getting the car running will be a big undertaking.

Oh, and how did you justify replacing brakes, control arms, etc etc on a car that you didn't even have running right/?? :shock:

(sorry, it's the pot calling the kettle black on this)

Using your list of "higher priced items", I don't see any that are high priced at all:

timing belt- $45 + labor
head bolts- $40 + labor
valve lash- FREE plus labor and a couple of beers
waterpump - $50 plus labor (about 15 minutes if you're already doing the timing belt)

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E30 2.5 running terrible

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