E420 5.0L engine swap does not start

[CGEGAG]

Hello everyone, first time writing a post here, it's been almost a year since I lost 4 chain guides on my 1994 e420, chain stretched and after doing the homework decided to go with a complete engine swap for a 1994 sl500.

While on engine stand, resealed everything possible, both oil pans, both main seals, o-ring for oil level sensor, valve cover seals, new water pump and thermostat, took off upper cam covers and resealed them, new bosch distributor caps and rotors, new oem cam magnets, new vacuum lines, new engine mounts. For lower harness I reused my old harness that was refreshed in 2021. Upper harness came updated with the engine. Installed a new starter as well. GSXR helped with LH and EZL, thank you.

At this point we only had a crank no start situation, tried starting fluid today, and yet, nothing... will be checking spark next, but if the car ran before engine swap, and now with new modules or even old ones, what would prevent it from starting. If we crank it until we smell burning wires from starter, on couple occasions it did run for a second, no mechanical noises or anything weird coming from the engine itself

 

[gsxr]

Nice project you have there! And the 5.0L engine looks very clean inside. I assume you checked cam timing with the valve covers off and all 4 cams are in synch. If the lower harness to starter/alternator was refreshed recently, that should be OK as well - this would not affect the engine starting. Don't crank longer than about 10 seconds at a time without allowing 10-20 seconds for the starter to cool, before cranking again.

If you tried starting fluid and the engine still did not fire, most likely there is no spark, OR the wrong cylinders are firing. Most likely cause of no spark at all is a bad crank position sensor (CKP), but first make sure it's connected tightly to the EZL (I assume it is). Measure the resistance of the CKP, it should be around 800-1000 ohms. Next up would be pulling analog blink codes from the EZL with a hand-held blink code reader, although since the engine has not started, I'm not positive if fault codes will be stored. Because the 4.2L engine had been running previously, the coils are probably ok as well.

The other thing to triple-check is the ignition wire routing and connections at the caps, and which coil is connected to which cap. The coil closer to the driver fender connects to the driver side cylinder bank (cyls 5-8), the coil closer to the engine goes to the passenger bank (cyls 1-4). See photos below.

Welcome to the forum!

 

[CGEGAG]

Thank you, timing at 44° all cams pins are in, that was the first thing I've checked before doing anything else, spark plug wires routed by these exact photos from above
, they where very helpful. The only thing I am mot sure about is which coil to which bank, will be checking all of the above by end of the day. Thank you.

 

[CGEGAG]

Success. Crank sensor 846 ohm, cam position 1101ohm.
Switched coil wires with places and started right up without starting fluid!!!
Following question, throttle body not responsive. Engine off and everything operates mechanically, as soon as I start the engine I can't open throttle not even if I push on it by hand.
Can I use throttle body of my e420?
Is 5.0L louder than 4.2L?
Engine runs very smooth otherwise, but only at idle, can't rev it up yet.

 

[gsxr]

Does your E420 have ASR? This was optional equipment.

The R129 has ASR as standard equipment, the ETA's are not interchangeable.

5.0L engine should sound the same as a 4.2L otherwise.

 

[CGEGAG]

I don't think it does, will double check tomorrow, but if I had ASR, I don't think I would be able to make donuts and have cruise control at the same time, without triggering any lights on dash.

 

[gsxr]

OK - assuming you don't have ASR, you'll need to use the original E420 ETA only. This will have a green label on it.

The R129 unit won't work properly, and will have a white label.

 

[CGEGAG]

Thank you so much for the help and patience! Looks like another project, but on the bright side we get to check the injectors as well.

 

[CGEGAG]

Swapped old ETA from e420, runs like a champ, way quieter then the first starts. Fixed starter problem, loose ground on starter, after a little drive had a misfire and have trouble keeping it running. Read couple of threads here to let ignition on for 2 minutes, is that yet my case? When accelerating it wants to die before it takes off, throttle linkages look kind of short, adjusted the cable enough so ETA is closed. Should I back it off all the way until it sits on the end position where spring goes? Took it around the block today, first time in almost a year! Thanks to all of you!

 

[gsxr]

Read couple of threads here to let ignition on for 2 minutes, is that yet my case?

Doesn't hurt, but this just lets the ETA synch with your T/LLR module. Won't cause misfires.

after a little drive had a misfire and have trouble keeping it running. ... When accelerating it wants to die before it takes off,

Misfiring after driving for 10-20 mins is almost always moisture in the distributor caps. Read this thread, inspect everything, cut the vent slots into the caps.

throttle linkages look kind of short, adjusted the cable enough so ETA is closed. Should I back it off all the way until it sits on the end position where spring goes? Took it around the block today, first time in almost a year! Thanks to all of you!

ETA should be closed AND the linkage resting against the idle stop on the ETA body. There should be a small bit of play at the end of the cable by the spring, the cable should not be pulling on the linkage at all when at idle position.

 

[CGEGAG]

Hello, opened everything back up, all the way to spark plugs, 1,4,6,7 unplugged, engine runs the same, distributor caps and rotors are brand new bosch, switched places left to right and right to left, same thing, looks like my coil is out, all wires are fine, both coils look original from 1994. Can there be something else.

 

[gsxr]

Did the engine run normally at first, then start misfiring? Do you have spare coil wires to test with by any chance?

 

[CGEGAG]

Adjusted linkages as they should be, little free play, all vacuum lines are fine. Misfire started after i revved it up, or at least it was way more noticeable, i think it was there before, that is why it almost died on me when i took off and I blamed it on the buterfly not being closed all the way, yes have all spare parts from 4.2 except the coils, new coils coming tomorrow from dealer, just to eliminate the possibility. Now it all makes sense why it didn't start at all at first with any of LH modules and EZLs until I switched coil wires, one coil dead and other one was sending spark to wrong cylinders...

 

[CGEGAG]

hello, replaced both coils, one of them was original, the one on a side was newer. nothing has changed, now that I'm writing this I realized that i missed checking if coils are getting power, will do that tomorrow, runs smother but yet only on 4 cylinders, i think I'm getting fuel in them , you can smell it outside the tail pipe. Where else can I look? unplugged 1-4-6-7 no change on how engine is running. what is feeding the coil for 1-4-6-7?

 

[gerryvz]

There are only two things that will control an entire bank of cylinders not firing - the coil for that bank, and the EZL.

The EZL controls the spark that is delivered to each bank's coil, so it is a single point of failure. If both coils are good, then basically the EZL is the only other thing that could be bad.

EZLs will either fail where one bank of cylinders dies, or both banks die in a no-start situation. I had the former happen to me in early 2009, and had to replace the EZL. Fortunately I had just purchased a spare.

Exact same symptom -- rough running (the car sounded like a flat-four Subaru) and plenty of gas smell coming out of the tailpipe. Don't run the car if you can help it, as the gas will poison the catalytic converter.

You should install a spare EZL for a 5L car and see if that solves the problem. A 4.2L EZL will likely run the car (both banks if it is good) and work as a short-term experimental/test EZL, to isolate if your existing EZL is bad.

Bosch EZLs tend to have a higher failure rate than Siemens branded EZLs, FYI.

 

[CGEGAG]

Exact same symptom -- rough running (the car sounded like a flat-four Subaru) and plenty of gas smell coming out of the tailpipe. Don't run the car if you can help it, as the gas will poison the catalytic converter

Thank you, what is catalytic converter... car only has one AUDI S8 muffler in the place of the resonator and 2 S8 front pipe cans modified and used in place of the muffler, all original exhaust is gone, except the manifolds... Sounds amazing... wish I could upload videos here

 

[CGEGAG]

I

EZLs will either fail where one bank of cylinders dies, or both banks die in a no-start situation. I had the former happen to me in early 2009, and had to replace the EZL. Fortunately I had just purchased a spare.

I have the original 420 EZL, another spare 5.0 EZL, but this one on the car came from a trusted source that is why i don't wanna blame it yet, I will try the spares tomorrow and see what happens, what can cause and EZL to fail, can something on the car, fry it?

 

[CGEGAG]

Here is a sound of it from 2024

 

[gerryvz]

Yes, typically heat will kill it. That’s why you should also renew the thermal heat sink paste between the EZL and the fender when you re mount it. There is a HOW-TO for doing this here on the forum.

 

[CGEGAG]

Hi, after playing around with 3 EZLs one of them is original to the car, switching power supply cables around short to passenger side and long to driver side, all the same. What else can control the EZL ?

 

[gsxr]

The EZL is basically a standalone item, although it does communicate to the other modules via CAN bus.

Can you identify which 4 cylinders are not firing? And if you swap distributors parts left to right, do the SAME 4 cylinders not fire? A defective cap or rotor, if swapped to the other side, will still result in running on 4 cylinders (just different ones).

Also - can you pull fault codes from all modules, including the EZL? Then clear all codes, start the engine, and see what faults (if any) return quickly. A handheld blink code reader will suffice, since I assume you don't have access to SDS / HHT-Win (factory diagnostic tool).

 

[CGEGAG]

Tried switching caps left to right, same 1-4-6-7 I can pull all plug wires while engine is running and nothing changes, definitely not getting spark to them, I will update once I have any diagnostic codes available

 

[gsxr]

Tried switching caps left to right, same 1-4-6-7 I can pull all plug wires while engine is running and nothing changes, definitely not getting spark to them, I will update once I have any diagnostic codes available

Got it. Same if you swap rotors left to right? Still 1-4-6-7?

 

[CGEGAG]

Did not try to swap the rottors, didn't see any burn marks or wear, but will try that as well today, thank you

 

[CGEGAG]

Hi, please let me know if I'm wrong, since I did not yet get HHT-WIN, playing around in the garage now, here's what I have found. From multiple threads and experience on here, I understand that distributor rotor adapters are not interchangeable, I have 2 same ones in there. From photos on forums, I can see that one adapter has alignment cut almost aligned with the center and then the other one is a few degrees off. I have 2 identical adapters on both sides

 

[gsxr]

Those appear to be the late / new-style rotor brackets. Those are correct, and the same one is used on both sides.

The original, old brackets are a slightly different design and IIRC, the currently available rotors won't fit on the old brackets. Pretty much all of the old stuff was replaced back in the 1990's though. I've never actually seen an original bracket (or, rotor) in the wild.

The slot on the back side which keys into a pin in the exhaust cam sprocket should be in the same position on all brackets. None of this affects ignition timing though, that is entirely controlled by the EZL.

 

[CGEGAG]

Thank you, that clears the brackets, switched everything from left to right, brackets, rotors, caps, now car does not start at all and only pops through the exhaust, I think I'm getting close, rotors are Bremi, caps are brand new Bosch but number 7 and number 8 sealing around the cores has leaked out... Ordered a new set of Beru caps. On these new Bosch caps center core looks like it has been chopped with a machete. Also pulled all the spark plugs out, 1-4-6-7 clean but wet, 2-3-5 nice but slightly wet, will reinstall everything back once new caps arrive, should all be dry by then