Car not running even after reverting to good map

Couple of evenings ago I tried playing with the warm up enrichments on my car to see if I could get it idling better from cold. I saved the old map and settings before changing anything. I didnt have much luck with the new settings so decided to revert to the saved good map. Once loaded the car still ran rough and I struggled to keep it running with the throttle. Thinking I might not have saved the good map properly I even got Eddie to email me a back up of a good map for my car. Still got the same issues once this map was loaded onto the ECU.

One thing I noticed was the dials in megatune flickering when connected to the ECU. This maybe because I was using a newer laptop and usb-serial adaptor. I then loaded the map with an older laptop using a straight through serial cable. With the older laptop the dials were fine but still having the same issues with the car. Other things I have noticed is that the TPS reading goes back down to zero when the pedal is fully depressed, I tried to recalibrate but still the same.

Can anyone notice anything out of the ordinary from the screenshots below?

First one shows two starts and stalls


this one shows when I tried to keep the engine running with the throttle

 

Basic spark and fueling checks needed before you start adjusting calibration.

TPS does sound suspect though. Have you tried switching it off? Values should increase as you press the pedal IIRC

 

Do you have a wideband on it? If so its running very lean. Recalibrate Tps with ignition on but engine off.

 

yes I have a wideband on it. I tried loading the good map a few times. On one occasion I had a low voltage warning on megatune. The wideband has come up with E9 error a couple of times which is also low voltage. Could this be significant?

 

Looks like it. is your battery/ Alternator ok?

 

I use the car daily and as far as I know all is well, however I tried starting it yesterday and it struggled to turnover a bit and the clock on the mfa zero'd out too but the car did start and still ran like crap.

 

Check the earths on you ecu and wideband. Maybe test voltage at battery when engine running and not running.

 

i managed to get the car running with a bit of throttle, very rough but running. Pulled off each ht lead from spark plug whilst running. It made no difference to the engine when lead# 4 was pulled but it was sparking away. I thought the injector must not be working so I pulled the rail to do the jam jar test and all 4 injectors had squirted the same amount of fuel. I checked the wiring of the fuel rail but that all checked out.

Another thing, I only got the car to stay running like this after pushing the required fuel setting from 20.5 to 23.5. With the lower value the car kept stalling even with throttle. I was convinced injector 4 would have been messed up but now Im stuck again.

 

The fact that it's showing very lean on the trace above makes me wonder if there's something more basic going on that's causing it to be starved of fuel. I'm half wondering if the lift pump has died. Apologies for not re-reading the whole thread, but have you checked that? Sudden drop in fuel pressure could cause the rough running you're seeing, so increasing the injection quantity has improved it a bit, but not removed the root cause of the problem?

You'd get the same fuel at each injector, but not enough from any of them to keep it running happily.

Guessing, but it's fairly quick and simple to check.

 

pretty sure compression is good in 4 anyway as I had it running with no plug in it and it was pushing air out with force but again something to add to the list of checks

Im now going to do a search on how to test the lift pump because I dont actually know how. I've replaced it before in this car I think. I knew it was knackered then as you could hear the main pump being overworked.

 

Pull the electrical plug from the main pump, and you should hear the lift pump buzz as it primes.

 

as easy as that! lol

 

Yep, but you do have to lie under the car in the cold and damp, if that makes you feel a bit more manly doing it

 

Went for a look at this tonight, to see if I could help figure this one out.

The fuel pump runs normally, nice and quietly. Fuel pressure is normal (5+ bar from the pump, 3.0 bar when you open the tap to the FPR. The pressure doesn't drop off when the car is running.

I fiddled with a lot things and wiggled a lot of connections. Nothing obviously wrong or made a big difference. The car misfires badly when cold, and gets smoother as it warms up, but never idled as smoothly as it should. It gets worse when you try to rev it. There's plenty of fuel at the fuel rail, but the car is behaving as if it's starved of fuel. We upped the 'required quantity' to the max, and it runs a little bit better, but not right.

So, onto the Megatune screen - the parameters look about right, except there are readings on the MAP sensor that I don't understand.

It's about 95kpa when the engine's off, or when the pipe is unplugged - fairly normal.

It's about 40kpa when the engine is idling - fairly normal.

BUT, when you open the throttle the kPA reading drops to the 30s, whereas I'd expect it to go up, as the throttle opens and vacuum collapses.

So I'm reading this as, because the MAP sensor kicks out a dud reading, the fuelling and spark doesn't adjust to suit the open throttle, so it doesn't rev cleanly and leans out the mixture till it starts missing.



So I think the diagnosis is a faulty MAP sensor, but I'd have thought a map sensor would either work or not, rather than give sensible readings for atmospheric pressure, and at tickover, but not when the throttle is opened?


Any ideas?

 

Went for a look at this tonight, to see if I could help figure this one out.

The fuel pump runs normally, nice and quietly. Fuel pressure is normal (5+ bar from the pump, 3.0 bar when you open the tap to the FPR. The pressure doesn't drop off when the car is running.

I fiddled with a lot things and wiggled a lot of connections. Nothing obviously wrong or made a big difference. The car misfires badly when cold, and gets smoother as it warms up, but never idled as smoothly as it should. It gets worse when you try to rev it. There's plenty of fuel at the fuel rail, but the car is behaving as if it's starved of fuel. We upped the 'required quantity' to the max, and it runs a little bit better, but not right.

So, onto the Megatune screen - the parameters look about right, except there are readings on the MAP sensor that I don't understand.

It's about 95kpa when the engine's off, or when the pipe is unplugged - fairly normal.

It's about 40kpa when the engine is idling - fairly normal.

BUT, when you open the throttle the kPA reading drops to the 30s, whereas I'd expect it to go up, as the throttle opens and vacuum collapses.

So I'm reading this as, because the MAP sensor kicks out a dud reading, the fuelling and spark doesn't adjust to suit the open throttle, so it doesn't rev cleanly and leans out the mixture till it starts missing.



So I think the diagnosis is a faulty MAP sensor, but I'd have thought a map sensor would either work or not, rather than give sensible readings for atmospheric pressure, and at tickover, but not when the throttle is opened?


Any ideas?

 

What he said ^^

Thanks for spending some time on this Mike really appreciate it. As I explained before this issue only started when I plugged in the new laptop with serial usb adaptor I did not touch anything mechanical prior to this issue and its been running fine for months. I noticed flickering dials on megatune when the ecu was powered up. Also noticed values changing randomly evertime I clicked on 'fetch from ECU' Could I have damaged the ECU in some way? thats the only other thing I can think of at the moment.

 

Ahhh clues. I used to get an issue where water used to get sucked into my vacuum line to the map sensor. This also used to freeze in winter. With the engine off ,pull the hose off from the ecu end and blow through it to make sure it's clear. You can also disconnect it from the engine end and suck on it with the ECU powered to make sure the MAP sensor moves the load up and down the map correctly.

Also check to make sure the line isn't collapsing. Just fit a new length to avoid issues.

Gurds

 

Thanks Gurds I'll do the checks above but still not too hopeful due to the nature of how the problem came about but you never know.