Bewgy

Hi Guys,
Long story short, I built a DIYPNP connected it to the car and could not get the car to start. Now I have removed the DIYPNP and reconnected the stock ECU and the car will not start, I have checked it is getting fuel and spark and I am quite sure the timing is correct. Any ideas what the DIYPNP could have damaged?
The car is a kit car Exocet type I have been driving it for a year with no problems. The DIYPNP was the first stage to a turbo! So I am stuck on step 1 :(. Hoping someone can help.

dleavitt

iTrader: (1)

To clarify: the engine is turning over correct?

If you are getting fuel and spark, then the DIYPNP itself didn't damage anything. The TUNE you had on the DIYPNP could...potentially...in very extreme circumstances that would basically make this all your fault. Maybe the tune had too much fuel injector pulse width and you flooded it? How many start attempts with your stock ECU.

Bewgy

I have tried multiple 3-4 times to start the car, that what I can't figure out how the DIY could damage the car.

Bewgy

Yes the engine is turning over.

Soy

check your spark, check your fuel and report back.

Bewgy

I have spark, checked with screwdriver in plugs. I have fuel, removed hose after fuel filter and it was a nice steady flow.

codrus

You've checked for spark at the plugs, but you've only checked for fuel at the input to the rail. Are the injectors firing? If you crank it and then take the plugs out, do you smell gas? If they're not firing not (which it sounds like is probably the case) then you need to figure out if that's because the ECU isn't commanding them to fire (which would probably point to a sensor problem) or if it's trying to fire them but it's not working for some reason.

Two things come to mind. Did you solder and wire the ECU yourself, or did you buy a pre-built box? If you assembled the ECU yourself, are you sure you wired everything correctly? If you miswired it and put power onto lines that weren't expecting it then it is possible to have damaged some electronic components in the car. Probably not the injectors, but possibly one of the sensors that the ECU depends on. If you bought the ECU pre-built then while this is still theoretically possible it's much less likely (the guys at DIY know what they're doing and build enough ECUs that they are unlikely to have made that kind of mistake)

The other possibility is that while you were installing the ECU you may have disturbed something in the wiring harness. This could be damage that you caused (did you yank on anything?), or it could have been damaged during the kit car build. Did the builder cut up the wiring harness to shorten it or remove unused wires? If so those are potential causes, and it's possible to have a loose connection that seems to work fine but when you gently pull on it (in a way that would normally be fine) it stops working. Of course even if the harness wasn't damaged during the build, it's a 20+ year old donor car and these things do age out.

The right tool to figure this out is an oscilloscope.

--Ian

Bewgy

Thanks Ian, I will check the injectors. That all make sense either a damaged sensor or dodgy wiring. I will check tomorrow. I built the car sooner have myself to blame .

The Diypnp build is a whole other story.

I am sure the build was ok because on my first attempt of installing i had the car running. But it stalled because i had not built the charging circuit correct. The 1999 mx5 has the voltage regulating circuit in the ECU, you have to build it yourself in the proto area of the Diypnp. When I rebuilt the charging circuit I damaged the 50 pins connect with the soldering Iron. So I had to replace it. However that's when all the trouble started the computer does not connect to the ecu and car did not start and made some very funny sounds.

So before i try to takle the dodgy soldering on the diypnp i want to get the car started again. Irl let you know how i get on.

Reverant

iTrader: (10)

Check if the plugs are wet from trying to start with the DIYPNP, which may be your actual issue.

Bewgy

I cranked her and then pulled the plugs, they was dry as a bone and not even a whiff of gas. So I think the problem is the injectors are not firing, Now I have to try and figure out why, looks like some research and testing this week end. Any ideas welcomed!

thebeerbaron

iTrader: (1)

Check the fuse supplying the injectors and then double check all your grounds.

Bewgy

Checked the fuse and earth all good. So i went to check the connector to the injectors, remove the air intake and found the connector to the was loose ?! Pushed it home properly and the car started, no idea how this could have happened I have not been near the connector for ages. It mush have been coming loose for a while. Anyway its running now I need to fix the DIYPNP! At least I can drive the car for the summer thanks for all the help and advice.