too much detonation

[pig4bill]

I'm having a problem with excessive pinging. I bought this car awhile ago and it pinged like a madman with the gas(unknown) that was in it. I just put 100 octane in it and it runs much better but it still pings under very heavy load.

I bought it as a bit of a project. The M20 engine was rebuilt as a stroker by the previous owner using an eta crank and pistons milled 3 mm. It ran too lean and he didn't want to invest more time and money to get it running right. I took a chance and put 19 pound injectors in it but it still pinged like crazy, but somewhat less with the 100 octane. So now what else can I check to get it running right on 91 octane?

- Timing advance, which I haven't checked because I don't have a timing light here.

- Fuel pressure regulator? Is it possible it's not getting enough fuel? It runs smooth other than the pinging.

- ECU? Is it possible the ecu is not sending enough fuel? It seems unlikely because it runs smooth otherwise?

- O2 sensor bad? Ditto the above, it seeme unlikely the sensor is bad because it runs smooth at part throttle, no smoke or anything.

Any other ideas?

[Jordan]

What chip is in the ECU? Sounds like a aftermarket chip designed for a stock 2.5l

When I had my 2.5l I had MarkD's 93 oct chip. Ran great with that motor.

The same chip in my 10.2:1 2.8L produced heavy pinging throughout the entire RPM/load range.

Swapping back to the stock chip made it about 10% as bad.

Fully custom tuning, HFM conversion, and a UNIChip piggy back unit cured the pinging.

[pig4bill]

I don't know what chip is in there. I guess I need to take a look. Do aftermarket chips usually have a vendors label or something like that on them? I've never bought an aftermarket chip because my other stock BMW (M42) had trouble enough running on crappy California 91 octane.

[Jon325i]

I don't know what chip is in there. I guess I need to take a look. Do aftermarket chips usually have a vendors label or something like that on them? I've never bought an aftermarket chip because my other stock BMW (M42) had trouble enough running on crappy California 91 octane.

Usually there is some kind of marking(s) to help identify what brand of chip is in there. I would try Jordan's suggestion and drop in a stock chip to see what happens.

Jon

[pig4bill]

Are all stock chips the same for the 2.5 i engines? Obviously I won't have a stock chip to put in if the one in there is aftermarket, so I'll have to ask for the proper one to put in. Or did different Motronic versions use different chips?

[pig4bill]

Okay, I've used up today's allocation of sweat and swear words and finally got my ecu out. It looks like the tabs are untampered with so it should still have the stock chip. I'd really rather not open it up if it's unnecessary.

http://tinypic.com/51owzk

http://tinypic.com/51ox2b

I have 19 pound injectors, so I should have plenty of fuel if the fpr is really putting out 3 bar. Is there an easy way to test it?

What other options would I have? Back off the advance at the distributor? Does the ecu control advance at all? The car is dead stock other than the stroker and I plan to keep it that way, so I'd really like to avoid the expense of doing the MAF and Unichip that Jordan did. It wouldn't be legal for California smog anyway.

edit: Crap, the image tags aren't working. You'll have to click the above url's.

[Jordan]

That ECU hasn't been opened. Stock chip.

You do not have any means of mechanically retarding timing. You need to have a custom chip burned, or go piggyback. There is no reason why you can't piggyback with the stock AFM, and with a MAF. You can save multiple maps and swap them.

With the cool adapter harness I made for my HFM I can go back to AFM in like 5 minutes! Not that I ever would...

[pig4bill]

That ECU hasn't been opened. Stock chip.

Thanks, that's what I thought.

You do not have any means of mechanically retarding timing. You need to have a custom chip burned, or go piggyback. There is no reason why you can't piggyback with the stock AFM, and with a MAF. You can save multiple maps and swap them.

So it won't do any good to try and retard the distributor? I've never messed with it, my other e30 has an M42 with no distributor.

With the cool adapter harness I made for my HFM I can go back to AFM in like 5 minutes! Not that I ever would...

I get what you're saying, but I'm in a Catch-22 situation. I need to pass California emissions on both the visual check and sniffer at the same time. So if I need the Unichip to pass, I can't remove it to get it smogged.

Also, this was supposed to be a budget project. I can't afford $500-$1000 for a Unichip and custom tuning.

[Jordan]

Sell the motor.

Buy a stock m20.

Drive it.

[pig4bill]

That solution did cross my mind. Unfortunately this motor is bolted into the car and I have no reasonable way to get it out or a different one in. The last time I paid a shop to swap motors it cost me $2500 in labor.

[Jordan]

Fly me out.

[pig4bill]

You can fit an engine hoist in the overhead bin? :)

[Stevens]

id try at least adding a feul pressure regulator and gage , set it up from 3b to 3.5 , try it , with those injectors you got on it, if still not ok, id put 535i injectors and go for 3.5b to 4b max with all injector o rings new !! and the feul regulator as wll :D it should stop a lot of the ping if not all it should literaly be to rich whatever the M20 strocker conv.

if it still pings i'd try to run it with the 535i complete ecu ,

if it still ping nothing cheap will save it.


good luck

[pig4bill]

I already have brand new 19 pound injectors in there. At 3 bar they can support 240 hp so there's plenty of fuel headroom.

A complete 535 ecu? Will the connector fit? I'm not too crazy about the idea of hacking up my harness.

[ultima]

Fly me out.

Hmmm....hey would you be willing to fly out to Vegas? I pay for the ticket and provide shelter, you party and swap in my engine? How much would you charge to do the whole swap? I've got access to a bay, lift, and all the tools you basically need. I'm sure TimmyBigHands could use you out here as well. :D