Starts then dies after S52 swap in Track Rat

[wake74]

Haven't posted in forever, as I've been focussed on a TR6 restoration project. I finally got around to putting the S52 in my '96 328 track car. Starts up and runs fine on my M52 DME that has a Shark Tune in it. Haven't had it out of the garage yet, but runs fine on the lift.

I purchased what was sold to me as a Manual S52 DME with EWS delete, as run in another track car a year or so ago. This project has been a while in the making. Tuned by Markert Motorworks in Atlanta.

When I swap in the S52 DME it cranks, fires and immediately dies. Almost like someone is cutting off the fuel or spark. My impression was that an EWS problem would cause a no crank. No strange CELs using my handheld scanner, next up is to pull out my old laptop with INPA on it, and see if anything stands out with that.

Thoughts?

Thanks!

[olemiss540]

I am sure someone else will have better feedback, but I would lean towards EWS issue IMO. EWS can have multiple symptoms depending on which part of the system is not working properly. Hope someone else weighs in with more specific s52 knowledge.

[wake74]

Went out to use INPA and realized my cable is in the trailer in storage, and not in the shop :-( So a no-go on INPA.

Here is one more tid-bit, I just disconnected the MAF and it starts and runs fine, idling in the shop. I wonder if the tune was for the commonly used larger MAF, but I don't know enough about the larger MAF to know if the DME would only work on one or the other.

[olemiss540]

Weird. When you say it "immediately" dies, actually how long does it run before dying? The car with the maf unplugged is running open loop, which it will also do when cold for a bit of time.

[wake74]

Weird. When you say it "immediately" dies, actually how long does it run before dying? The car with the maf unplugged is running open loop, which it will also do when cold for a bit of time.

A very short period, 2-3 seconds

[ScotcH]

temp sensor can cause the DME to not know the car is cold ... It's gotta be a sensor of some sort. Start with the easy stuff. But could also be tune as you say ... if the MAF is mismatched to the tune.

[wake74]

temp sensor can cause the DME to not know the car is cold ... It's gotta be a sensor of some sort. Start with the easy stuff. But could also be tune as you say ... if the MAF is mismatched to the tune.

Double checked that, as I actually missed that on initial start-up on the M52 DME, and got a CEL for inlet air temp. But that's currently connected correctly. The thing that is confusing me is that it runs fine on the M52 DME with no CELs

[ScotcH]

Double checked that, as I actually missed that on initial start-up on the M52 DME, and got a CEL for inlet air temp. But that's currently connected correctly. The thing that is confusing me is that it runs fine on the M52 DME with no CELs

I meant the water temp sensor actually, but yeah, if it runs with the m52 DME, that's probably not it. You might need to contact the seller or flash company to see what mods the chip is for. Or try to source a stock DME.

[wake74]

I've contacted the seller, who apparently was selling it for a friend. Willing to help but short on details. He thinks he may have had a 3.5" MAF either the Porsche one or the 540 one. I'll double check the temp sender in the block, but it should be connected. I can see coolant temp data live on the hand-held when running with the M52 DME.

It was tuned by Markert Motorsports in Atlanta, which stopped being a performance / tuning shop a couple of years ago it looks like and now just does maintenance. I'll reach out to them and see if they maintained any records. The DME does have some very non-factory paint pen markings so someone marked it up for a reason.

Unfortunately, I don't have a manual S52, only an auto DME. The swap engine came from an auto car.

[BlackHawkRacing]

Can confidently tell you it's not the EWS. Car would not turn over at all if it was EWS; fuel pumps wouldn't even prime upon power up.