Engine swap issues..

Mattstrike

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Ok, so the short of this is, K2500, 3800 series one, twin T25 turbos, running on an OBD 2 setup connected to a 700r4. Start cold, it fires up, idles down, immediately misfires and dies. If you give it throttle, it fights through the misfire and will run mostly smooth at about 2k rpm. If I let it warm up it will idle, but the misfire sounds like it's got a huge cam, and the exhaust pours out white smoke like crazy. It either smells like fuel or oil, I can't tell.

Using series 1 L67 fuel injectors, a 2005 GTP MAS, series 2 knock sensors, series 2 MAP sensor, and everything else is stock 1991 series 1 3800 shit (TPS, IAC, IAT, crank and cam sensors, type 2 ICM and coils, etc...). I recently added O2 sensors (from a '04 LS) as that's what I had on hand. Wire harness started out as a '98 Bonneville harness, I've nipped and tucked it to fit this application... so everything got nipped, only the bare minimum to run the engine was kept.

The turbos have a 7/8" drain straight down into a vented tank. An electric pump pulls oil from it back to the oil pan. When I ran it like this (after making the change to 7/8 drains and pulling the exhaust to add the O2 sensors) no oil was leaking out of the turbos anymore so I put the rest of the exhaust back on to find the white smoke show, as well as oil starting to pool in the intake side of the left turbo. The right exhaust blows more smoke than the left thus far.

The only codes being set are for P0300, so that just means the PCM has no clue (as usual). Coils seem to be firing, I can't narrow it down to a specific cylinder other than #6 yet (based on scan data showing a trend to misfires on #6). But that was before adding both upstream O2 sensors.

I've swapped the coils around with known working ones, doesn't seem to help the issue. I've also swapped ICMs. I still think that the coils are firing weak though, the spark won't jump the gap from the post to the screw on two of the coils, doesn't matter what coil is where or what ICM I use. They are sparking, just seems weak to me.
 

RICH17

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Quite the combo. For some reason I didn't think the S3 maf works in older stuff? Did you wire it in?
 

Mattstrike

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Yes, the MAF is wired in. It's not the style that bolts onto the side of the throttle body, it's the one with its own housing that I've got clamped in front of the throttle body.
 

RICH17

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Unplug maf. Try to let it run like that. Has symptoms of a bad maf to me. Unplugging it would clear up the idle if it is bad.
 

Mattstrike

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I have messed around with that a bit. I know that when we scanned it before we were seeing data from the sensor.

If I unplug the MAS now there is no discernible change in the symptoms.

Other factors/working theories I'm chasing are any differences between the CPS and balancer (there was a change in '93 to a non-adjustable sensor), in case the timing is off slightly; also the flow rate of the fuel injectors. I'm using series 1 L67 injectors, I don't know if the series 2 injectors are the same or will fit the rail.
 

PANDA

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James would probably be the only guy to help you out.
[MENTION=53]Turbocharged400sbc[/MENTION]
 

boostedguy05

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Yes, the MAF is wired in. It's not the style that bolts onto the side of the throttle body, it's the one with its own housing that I've got clamped in front of the throttle body.
if i remember right, the S3 MAF's are designed to work with a 4-6" gap between the MAF and the throttle body. not sure if it will really make a difference but might be worth a shot.

are all your grounds good?
 

Mattstrike

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So, not sure what I really did with the MAS, but the series 3 sensor is 5 wires not just 3. Looks like I have a +12v switched, a signal wire, and a ground, leaving the other two wires, whatever they are, open.

I have about 4" between the sensor and the throttle body (silicone coupler). Didn't know the distance mattered, but should be close enough?

Every individual ground goes to a common ground point on the fender, that ground has a 4 gauge wire that runs to the main ground block, where both batteries and the engine block and the frame ground wires all converge. So unless I missed a sensor ground wire, that should be all set.
 

Mattstrike

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That adapter won't help anything, I've already hard-wired in the correct connector for the MAS.

I had to dig through my notes, looks like the extra two wires are for a temperature sensor that I don't need.
 

RICH17

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I believe S3 maf sensors also measure IAT's
 

b4black

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Have you verified your fuel pressure? Wonky things happen when it way too high or way too low.

Also, the Series 1 ICM (and early SII) is grounded though the base mount. Might what to double check that.
 

MonzaRacer

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white smoke and oil pooling I thing I would be double checking engine integrity, Make sure all cylinders are same, within 10 psi.
I vaguely remember a guy by padding IAT from MAF and having issues. He was trying to use a remoted IAT. Seems the MAF used a reference inside if it fails or is unhooked it gave stupid readings on MAF side.
Verify engine, fuel, sensor signal integrity. run open loop with O2s unhooked THEN hook them up and let computer control things. adding 12 things then trying to diag makes job lot harder and not seeing what scanner you have, PIDS info. kind of like trying to diag a Megasquirt without aMSQ file or datalog.
 

boostedguy05

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So, not sure what I really did with the MAS, but the series 3 sensor is 5 wires not just 3. Looks like I have a +12v switched, a signal wire, and a ground, leaving the other two wires, whatever they are, open.

I have about 4" between the sensor and the throttle body (silicone coupler). Didn't know the distance mattered, but should be close enough?

Every individual ground goes to a common ground point on the fender, that ground has a 4 gauge wire that runs to the main ground block, where both batteries and the engine block and the frame ground wires all converge. So unless I missed a sensor ground wire, that should be all set.
the 04+ maf's read everytrhing togther. you cant just re-wire it for what you want it to read, it wont work right. either use a pre 04 maf or you need to get an adapter so the maf thinks everything is beign sent so it will work right.
 

Mattstrike

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Does anybody have a wiring diagram for that sensor? I'll have to revise my wiring if that's the case.
 

boostedguy05

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And it's not an engine swap issue, it's a frankinfuckingtruck issue. : rolf:
 

Mattstrike

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Well, hooked up the other half of that sensor, no dice.

I ended up finding out that I never put the new spark plugs in, the #6 plug insulator was broken, guess I forgot about that. Fixed the misfire on that cylinder, but not the problem.

But I think I found a vacuum leak by one of the fuel injectors now. So I just grabbed a set of tried and true stock series 2 L67 injectors and waiting for it to cool down to swap them over, makes the fuel side of the tune simpler.

I've noticed that the PCM is commanding less than 10 degrees of timing at idle. I marked TDC on #1 and used a degree wheel to mark off 10, 20, 30 degrees advance. The marks are saying 12-15 degrees of advance, when the PCM is commanding 7-10 degrees. So maybe my marks are a little off, just more data to consider at this point.
 

SleeperLS

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Fuck yes dude. Awesome set up. I don't have Facebook, but that small clip looks awesome.
 

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