engine swap m42 swap no start. gurgle gurgle pop.

[pklym]

We are baffled. Have been working on an m42 swap into my '76 for over a year now and the damn thing just won't start. I have had some threads over at r3vlimited that offered suggestions but nothing that has stuck yet, so I am reaching out here. The FAQ is much more active.

 

We have spark, we have fuel, we have excellent compression. The engine is timed properly. Every sensor ohms out fine. The wiring harness has been pinned out repeatedly and everything matches. We have tried two different ecus, two different crank position sensors, two different cam position sensors. The car has coil on plugs (because the spark plug wires that came with the car were busted), its got brand new coils. Injectors are the common ford four pintle injections that were rebuilt prior to purchase. They all seem to spray properly. Fuel pressure is in spec. Coils are in proper order 1-2-3-4 from front to back, we have tried other orders that some people have sworn work. Relays all have power, the power seems to remain constant throughout cranking.

 

The car cranks and wants to start but won't. Last week we replaced the crank pulley and it made a noticeable difference. Now it gets even closer to starting and backfires and pops and gurgles and sometimes even seems to start with one rev before dying. Below is a video though the phone doesn't pick up the sound that well.

 

One thing that has bothered us, and is possibly the cause of this, when we pull the coils and watch them spark (in slo mo video) they stop sparking after a few cycles (of wasted spark). It just seems to stop sparking completely. We would think this has something to do with the crank position sensor or the ecu but as mentioned, we have tried to ecus (both supposedly from working cars) and two CPS, both new, both ohm out correctly. We are definitely at the "throw parts at it" stage of troubleshooting. Right now I have an AFM on the way (though supposedly it should start with this unplugged, so we have tried both ways), and another (used) CPS (this one is a different part number, the original part number that was later superseded).

 

The r3vlimited threads are here: http://www.r3vlimited.com/board/showthread.php?t=384330 http://www.r3vlimited.com/board/showthread.php?t=391672

 

Video of a start attempt here: https://goo.gl/photos/ZGRHB9xRmQ8WfcrX7

 

 

[stuff]

Tried changing the polarity on the crank position sensor?

 

Couldn't get my Megasquirt build to run for weeks of fiddling with lots of popping and nearly catching until I flipped the VR sensor polarity, et voila, she purred like a kitten.

[TobyB]

Good one.  Unlikely on m42, tho.

 

I forget from r3v- have you put noid lights/ signal logger/ etc on all 4 injectors & coils?

 

Smoke test?  On Jim's 2002 last month, we randomly found 2 intake gaskets on port 3, and none on 2.  It was a

big enough leak to lead to a no- start....

 

The other thing I would do if it was me is go back to the OE coils.  Just to rule that out entirely.

 

fwiw,

t

 

 

Edited September 4, 2016 by TobyB

[tashakes]

At the risk of sounding stupid, do you have a solid ground strap?  Also, check the wire harness for any cracks especially the one going to the ECU, any short can prevent the engine from firing up.  Hook up your CEL if you have not and do the stomp test to see if you get anything that shed some light.  You have covered all the logical bases, now start looking for the basic dumb ones.  

[jimk]

Are those injectors the right size for the original setup.  People put higher flow injectors with an ECU that can't be adjusted for the new size and the added fuel makes trouble.  What do the plugs look like after the Gurgle, Gurgle, Pop?

[pklym]

13 hours ago, stuff said:

Tried changing the polarity on the crank position sensor?

 

Couldn't get my Megasquirt build to run for weeks of fiddling with lots of popping and nearly catching until I flipped the VR sensor polarity, et voila, she purred like a kitten.

 

As Toby points out, you can't really reverse it on this car. Thanks though.

[pklym]

12 hours ago, TobyB said:

Good one.  Unlikely on m42, tho.

 

I forget from r3v- have you put noid lights/ signal logger/ etc on all 4 injectors & coils?

 

Smoke test?  On Jim's 2002 last month, we randomly found 2 intake gaskets on port 3, and none on 2.  It was a

big enough leak to lead to a no- start....

 

The other thing I would do if it was me is go back to the OE coils.  Just to rule that out entirely.

 

fwiw,

t

 

 

 

Yes, we've used lights on coils and injectors. Injectors light up properly, coils do too for a bit before stopping

 

I think the smoke test is probably in order, intake has been on and off several times so I know we won't find two gaskets but maybe there is a leak elsewhere.

 

I think we still have the old coils so I would just need to track down some wires that don't cost a fortune. I will put this on the list.

 

Thanks

[pklym]

4 hours ago, jimk said:

Are those injectors the right size for the original setup.  People put higher flow injectors with an ECU that can't be adjusted for the new size and the added fuel makes trouble.  What do the plugs look like after the Gurgle, Gurgle, Pop?

 

They should be the same size just with 2 additional pintles. 

 

The plugs are wet and black, with 1 and 4 being wetter. 

[pklym]

11 hours ago, tashakes said:

At the risk of sounding stupid, do you have a solid ground strap?  Also, check the wire harness for any cracks especially the one going to the ECU, any short can prevent the engine from firing up.  Hook up your CEL if you have not and do the stomp test to see if you get anything that shed some light.  You have covered all the logical bases, now start looking for the basic dumb ones.  

 

Definitely grounded. Stomp test shows no errors. Thanks.

[KFunk]

It sounds like a timing issue to me.  You said it's timed properly, but how? I'd be suspicious about anything used for that.  I would be triple checking all timing marks, use a dipstick in the plug hole to verify TDC and verify by looking at cam, etc.. I don't know how to do it on the M42, but I'd be adjusting timing until it fires up a little. Then set it perfect with a known good timing light.  

[pklym]

38 minutes ago, KFunk said:

It sounds like a timing issue to me.  You said it's timed properly, but how? I'd be suspicious about anything used for that.  I would be triple checking all timing marks, use a dipstick in the plug hole to verify TDC and verify by looking at cam, etc.. I don't know how to do it on the M42, but I'd be adjusting timing until it fires up a little. Then set it perfect with a known good timing light.  

 

It definitely seems like a timing issue but its been checked about 100 times. Timing can't be too far off because compression is great across all 4 cylinders. Timing marks all line up. Cams line up properly etc.

 

The flywheel doesn't have the locking hole that is often used in timing but every indication is that the engine is in time. 

 

Thanks

[RogueDriver]

Have you verified the fuel rail is hooked up correctly?  Its easy to mix the supply and return lines up.

[TobyB]

Quote

wires that don't cost a fortune

Somewhere, there was a post about $25 wires that worked if you didn't mind the lengths being off, but I forget what they were from...  I think it was on R3v...

 

t

 

[pklym]

21 hours ago, RogueDriver said:

Have you verified the fuel rail is hooked up correctly?  Its easy to mix the supply and return lines up.

 

Yes, I've checked that a few times.

 

Would a bad FPR somehow relate to a no-start like this? The only method I have found for testing an FPR requires the car to be running. I really don't think its the issue but running out of things to test.

[dlmrun2002]

 When I had my 318is M42 rebuilt I screwed up on spark plugs wires and firing order. It was my fault when I misinterpreted the  numbers  1 3  4 2  or something.I forget..it was 10 years ago.  I  made a change on the coils and spark plug leads and she fired up. 

 

dlm ny country