New BP starting to act like the B6 I just replaced.

[im2bad4ya]

Well, I just did a BP swap because I was under the impression that my B6 had blown a head gasket. Although I didn't actually verify it with a mechanic, I had all the typical symptoms: rotten egg smell from the engine compartment, white/blueish exhaust smoke, bad timing, and the car wanted to stall when I gave it gas and it would drag (when I was driving and let go of the accelerator, car would feel like it was dragging, lack of power).

Well I got my BP swap done last week without problem, only I was driving without an O2 sensor. Yesterday night, the engine started giving me the same exact problems as when I had the B6. Only difference was the B6 engine didn't give me a check engine code, the new BP gives me a check engine light that stays lit after cranking. Even when I jump TEN & GND to pull up codes, the light stays lit, so there's no way to self-diagnos. I left my car parked for a half hour until I decided to check out what was going on again. Sure enough, I crank the car and the anomaly is gone, worked as if nothing was wrong. So I thought I was in the clear.

This morning I go to the post office to pick up a replacement O2 sensor, I get there with no problems. I return to my house park my car, install sensor with the intent of going out again, only had to pick up some books from my house. In and out in 5 minutes and when I crank the car, I have the same problem that started from yesterday: check engine light on, want to stall when I accelerate, bad engine timing and bad smell coming from the engine.

Now if I did indeed blow the headgasket, I'd be amazed, two blown engines within a month.....but what's peculiar are the similarities with the B6 I replaced with my BP engine (as far as this problem I have). Could it be something electrical or with the fuel system? I have hope for the fact that my car had these problems yesterday night and completely went away, only to come back, so my best guess is it's not mechanical (unless like I said, luck of the Irish, blown headgasket once again).

Has anyone ever had this problem before? I'm wondering whether I need a new fuel pump, there's a short circuit in the wiring somewhere, or if I need a new fuel injector relay? (I'm narrowing down the possibilites to parts that didn't get swapped out during the BP swap, I got a new fuel filter so that probably isn't it).

I took my car to a mechanic, so I hope he'll be able to pin point the problem, but otherwise I wanted to see what guys familiar with the ins and outs of an MX3 had to say.

[Sleeper6]

Out of curiousity what did your catalytic convertor look like when you dropped the motor? Bad acceleration and power band combined with the rotten egg smell are easy symptoms of a clogged cat. Not to mention that can cause a car to foul out an O2 sensor as your cars ecu tries to compensate. Personally Ild disconnect the convertor and take it for a spin around the block.

[im2bad4ya]

funny you should mention that..........

I had a new CC installed last May, then in July it craps out, I hear this noise inside it, like something came loose and it just rattles inside the CC. Since I had the two year warranty on it, I returned it and got a replacement. So I have a newer cat that was install in July. And the downpipe is brand spakin new since I couldn't use the old one with my particular BP engine. The muffler is also new from July. (that leaves the section of pipe from the catalytic to the muffler that's still original on the car, don't see how anything could be clogged there)

But being I replaced the engine, along with the computer, I'm totally suspecting that it's the fuel pump. (didn't replace the tranny, but don't see it as the culprit). So gonna put in a new fuel pump and strainer and see if this fixes it.

[im2bad4ya]

So got back my car today and my mechanic says he couldn't figure it out. I take it home, and try to troubleshoot on my own.

Just wondering if anyone knows, could I have a bad Main Relay???.....Like I said, the problem was on the other engine, now on this one, and it's down to electronic, fuel, or combination of both. I still have the check engine light but when I remove the Main Relay, the check engine light is gone, even when I go from ACC to ON on the ignition, the car obviously won't start without it, but the fact that I got the light to disappear, perhaps I have a bad Main Relay?

[Sleeper6]

When you remove the main relay you are disconnecting power to the ecu so it would make sense the cel goes away. If someone severed your neck Im sure yould stop blinking too!

Second question; did you try driving it with the cat disconnected yet?

Third I would be more tempted to think of a bad coil/dist if you let it sit and the problem goes away. This is a common cause of failed ignition modules that leads to bad spark, lack of ignition so more fuel dumped on the cat all that could cause your symptoms.

[Ryan]

Its so hard to help out guys like you... Its either the replacing s--- at random, or general bad practice (running without an O2, etc)

Check your fuses.

Disconnect the negative battery terminal, and hold the brake for 30s. reconnect the battery terminal, and start it up and drive around the block.

Pull the codes.

Start there, and quit introducing new variables, or I won't bother visiting this thread again. I don't mind helping people, but its not worth my time to keep track of whatever crap you're doing on a whim.

[im2bad4ya]

Duly noted Ryan, thank you.

I can't remove the cat because it's been welded on, so I can't test that.

All my fuses are good, checked the main relay and it clicks, although I opened it up and there is some discoloration on the coil, but I don't know if it's bad or normal.

Disconnected NEG battery cable, press brake for a minute, doesn't change anything, still get check engine light.


Unfortunately, I can't pull up codes because as I've said, the check engine light stays lit, when it's in the on position, after I crank the car, and when I go into self-diagnosis, the light stays lit.


Also the car sometimes doesn't turn on, cranking it is no problem, but now it has difficulty starting up. I have to floor the accelerator to feed it gas and when that doesn't work, I remove and put the main fuse back in it's place to get the car on.

I'm not changin s--- at random, just going by process of elimination....and hey, can't hurt (Ryan's referring to me installing a new fuel pump HOPING and not KNOWING this would fix it).

[Ryan]

Alright, if your CEL stays solid, there is something wrong hardware wise. Have you done any messing around with the harness? If you know your harness is tamper-free, try a new ECM.

http://www.mx-3.com/manuals/showimg.php ... F2-073.gif

That is your reference.

abnormal CEL operation:
-> make sure FUEL INJ relay operates normally
--->Shake it, it should rattle.
---> Apply 12v to the proper legs, should click, and click again when you remove the voltage
---> Should see infinite resistance across the other two legs with 0v, ~0ohms with 12v
---> with ignition ON, it should have power provided to it from the fuse box

-> make sure harness is working properly (our harnesses don't tend to fail naturally, only with tampering. This is not the case for Probes...)
-> replace ECM.

[im2bad4ya]

YOU SEE!!!....This is why you're Ryan and I'm im2bad4ya


In short (no pun intended) problem is a loose wire on the ECU end of the harness.

There are two cables that connect to the ECU (MTX). So according to the pins on the workshop manual [1A, 1P,2N, 2L, etc], we'll call them 'cable 1' and 'cable 2'. The only modification I did was add VICS pin 2S and splice wire 1B for the other VICS wire. At Ryan's suggestion, I swapped the BP ECU with the B6, and still no difference, the CEL was still on. I jiggled the cables around and the CEL flickered on/off............so there it is.

Cable 2 is fine, the problem is with Cable 1. I haven't (again, no pun intended) pinpointed which wire is short. It's not from the actual connector, I open it up and the pins are properly ceded. When I grabbed the bunch of wires from Cable 1 [between the connecter and where it snakes behind the firewall], the check engine light went off. I also took off the 1B VICS wire to make sure that wasn't it. [CEL still on after removing the VICS to 1B wire, grabbed the bunch of wires, and light went off again ]


So I've bunched the wires in a way where the shorted wire is making contact and I'll have no problems [putting a band-aid on it if you will]. I'll have to drive like this for the rest of the week until I have time over the weekend to get a multimeter and check all connections and properly diagnos and fix the wire.

So there are some wires on that cable which obviously aren't causing this problem (A/C switch, headlight switch, etc). This was a fuel/emissions problem at hand. If I had to guess, I'd say it could very well be 1B (Main Relay) or 1N (Throttle Sensor), 1G (Igniter) or 1K (Diagnosis Connector).

Any thoughts?

[Ryan]

If this is in the middle (not by a connector) it should be easy to find the problem wire.

If it gets out of hand, it may be time for a new harness. Any B6/B8/BP one will work.

http://www.mx-3.com/manuals/showimg.php ... F1-140.gif

This and the next pages will help you sort out any possible wiring issue. Its meant to be read in book form (two pages at once) so its a little difficult unless you print them out.

[im2bad4ya]

okay, made my 70 mile trip today with no problems, engine is running as it should, and I have no codes.........

Now I just have to solve the mystery of the high idle........

Car, when cold and after it warms up stays at 1.2K RPM. The Idle screw is all the way down, completely tight. This problem followed over as I had the same thing on my B6 and I'm using the same throttle body. I'm guess bad ISC valve but I'll have to check it.

[Ryan]

Have you set your ignition timing since the swap?

Where does the idle sit in DIAG mode when its warm?

[im2bad4ya]

haven't set it, but when I jump the TEN & GND after the engine is warm, there is no effect, idle stays the same.

[Ryan]

That... is how it should be, but is strange. Normally there's a 200RPM or so difference...


Quadruple check for vac leaks. (visual, propane/ether, sucking methods)

Then set the ignition timing and idle properly, and go diagnosing hardware from there.

[im2bad4ya]

I've checked for VAC leaks before, I don't think that's it, but will check again.

But I just realized that when I swapped over the pulleys, I didn't check the markings to make sure they matched up with the ones I took out. (ie. make sure the marking matched up, read BTDC, etc). Is that gonna screw me up or will I still be able to read the timing?