m30 running rough (NOW WITH VIDEO)

[BavBeater85]

damn, you said earlier that its a 292 camshaft? might be too aggressive...cams like that seem to be meant for high revving so without proper tune they wont run right at lower rpms (same concept as how big v8s with cams sometimes need stall converters)

[tfritz]

no clue how many miles it has, but my brother is the one who built the head and it cant have any more than 20k on it.

[mbonanni]

Very jealous man.

I will hopefully have an m30 swapped e30 someday.

How many miles does your motor have, and did you refresh it at all?

[tfritz]

^haha haven't driven it yet. Still needs the fan wired up, clutch bled, exhaust ran, and a few other little things.

[csermonet47]

Does it do mad burnouts?

[yert315]

called it. glad everything worked out!

[tfritz]

Just swapped the m20 harness today for an m30 harness and it fixed the issue!

[csermonet47]

If harness stuff is good, you have no vacuum leaks, and you have good fuel pressure, it can only be a few things. Have you done a compression test to verify all those numbers check out? You need 3 things to run properly. Air, fuel, and spark. Make sure all your plugs are firing correctly and have good spark. Take them out and look at them but don't try to run the car without a plug in without pulling the fuel pump relay (it is a good way to burn your garage down). Plugs can tell a lot. Also make sure all your injectors are firing properly. I bought rebuilt injectors and had one stuck open that caused all sorts of issues. Verify you are getting voltage to all of your injectors. Checking your timing wouldn't hurt either. Is the car smoking at all? You can also start swapping parts out for known working units. CPS sounds like a good place to start. If you don't have access to known working units, there are tests in the E34 Bentley book for them. If you don't have the Bentley, PM me and I can send you the test procedures.

[tfritz]

Also just tested fuel pressure and it is about 39-40 at idle, then I unhooked the vacuum at the regulator and the pressure jumps to about 44-ish.

[tfritz]

ICV hose appears to be fine

[Jean]

Surging can be caused by the idle control hose collapsing as well, double-check the hose from the icv to the intake manifold that goes down under the wiring harness.

[tfritz]

Okay, after talking with Brodi from miller, the MAF checks out. Also got a brand new tps. I STILL have this dang surging issue!!

[tfritz]

Well im pretty sure the MAF is toast, I tested for resistance and get nothing...
Also not getting any power to the tps plug...tps has a little click when turned, just no power going to it...

[Doughnut]

Okay, I put in a different ICV and may have had the ICV and TPS plugs switched :oops:....It starts perfectly fine and idles good but still have no throttle, when I give it throttle it just bogs down...TPS???

TPS will cause this issue, remove it and turn it with your finger, it should make a little "click" noise at idle position, and should move smoothly through its rotation.

AFM will cause this problem too but you have a MAF so...

[tfritz]

Okay, I put in a different ICV and may have had the ICV and TPS plugs switched :oops:....It starts perfectly fine and idles good but still have no throttle, when I give it throttle it just bogs down...TPS???