Engine still won't run properly

[Rory's Dad]

To recap, I have fitted new throttle bodies (because the original ones were stolen) reconnected everything and the C20XE now just won’t run properly.  Seems to run much too rich with lots of black smoke and flames out of the exhaust.  The plugs are dry, black and sooty and last about 15 minutes.

Well a little more progress.  Martin Fox (mefmotorsport) kindly came over to see if he could figure out the problem.  I knew that the tps sensor was incorrectly wired (it would sort of run wired wrong but ran worse when it was wired correctly IYSWIM).   Well Martin wired the tps correctly and then started on the DTA ecu.  He got it to run a bit better and better but found out that it needed around 100% more fuel so that pointed to an air leak either at the manifold or between the manifold and the Jenveys.  I took the car out for a run and it soon started misfiring and backfiring again so I turned round and limped home.

Well over the last week I have taken it all apart and unfortunately there was nothing wrong with my assembly.  There was a little tear in the inlet gasket between a stud hole and the outside edge (it was the original) and the “O” rings were all present and correct between the manifold and the Jenveys.

As a newbie, I’m out of my comfort zone and just don’t know what to do.  I can’t really afford to take it to Steve Greenald who did the original mapping as I have no trailer or tow hook.  However there is a guy locally who apparently knows his DTA but specialises in motorbike engines on grass track racers and MNR’s BECs.

My question is this - is there anything else I can do or check before I part with yet more cash.

Rory's Dad

[CedricTheBrave]

just to recap

do you have the ability to view the DTA setup?

can you see the TPS min TPS max and TPS raw settings? (not sure if they are called that on the DTA but they should show something similar!

can you run the car with the DTA plugged into the PC/Laptop?

[Rory's Dad]

Martin Fox could see the DTA set up, set min and max settings for the tps, ran the car with the DTA plugged in.  He also adjusted the settings using a DTA dyno control box which "...allows the user to modify the ignition and advance settings remotely".

Rory's Dad

[CedricTheBrave]

do you know what they were?

[Dave Eastwood (Gadgetman) - Club Chairman]

"...allows the user to modify the ignition and advance settings remotely".

Rory's Dad

Just to avoid confusion though, the pot box doesn't do anything you couldn't do from a laptop - it's just more convenient when mapping and you've got your hands full!

OK, so the TPS is now set, are you positive the other basics are done, not sure how much was stollen/damaged, fuel pressure? Is it what it should be? How about air flow at idle? I know it's tricky when not running properly, but is it pulling the correct air flow, and are all the barrels balanced? If not, have you got bleed screws on individual barrels, could one be set wrongly, and allowing too much air past, (assuming the comment about too much air is correct).

What exactly has been replaced, could it be that the new TBs are faulty?

[Dave Eastwood (Gadgetman) - Club Chairman]

do you know what they were?

You can reed these settings with DTA software, but just in case you're not familiar, the set up process is a case of mouse clicking on a button to say the throttle is at it's closed position, then clicking again to say it's at WOT. Obviously, having manually open the throttle or stood on the accelerator between times. Unless either end figure on the DTA readout is out of range, that's it. (And if it is, you just slacken and rotate the TPS a little and start again)

[Rory's Dad]

Gadgetman - the fuel pressure is fine (45psi/3bar)

Dunno about air flow.  I've rechecked the balacing when re-assembling.  I haven't touched the bleed screws.

How can the TBs be faulty?  They came frme SBD, as did the injectors (SBD's equivalent to 744s) the manifold, the 90mm trumpets and the throttle linkage - it was all like for like.

Rory's Dad

[Arm]

Also worth reloading the engine map. I've had to do that before.

[Crash test dummy]

Have SBD supplied you with the right injectors? Do they have a part number on them that you can check?

What sort of figure was showing in the fuel map cell at idle or thereabouts? Something around 2.5 - 2.8 should be OK enough as a starting point on creams with 3 bar.

When you rev the engine with the mapping screen on view does the curser dance about the fuel map as you would expect or is it erratic. Just revving it gently in the garage should keep the curser in the high speed low load area. If it flicks up into the high speed, high load area (ie lots of fuel) that could indicate a sensor problem. TPS usually but could be the crank sensor also.

Are the temp sensors all connected and working OK. Could it be running on the cold start map constantly?

[perksy]

Some Good points above to try

Also when the engine is Cold check that the Air temp' sensor and the Coolant Temp sensor are giving very similar readings

*If* the Coolant Temp sensor is playing up and it thinks the engine is VERY Cold it will b****r the fueling up by supplying excess fueling

a friends VX had a similar problem to this and in the end the ECU went back to SBD for repair..

Think the Spark Plugs will also be past their best by now aswell      

[Thrustyjust]

make sure you have balanced the throttle bodies also. One of mine had no air going in and made it all seem like it was running rich.

[Rory's Dad]

All sorted now courtesy of Damian at Daytuner...

See here for the happy end to this story.

Sometimes spending money is the only way forward  

Rory's Dad

[Kevin Jones]

Glad you got is sorted at last, did damian just remap it for you in the end or did he find something odd in the new install?

[Rory's Dad]

It was a full remap Kevin.  To show me what he had been up to, he copied 60+ maps onto my memory stick which I can see on some cut-down (and free) Dynojet software.  I need to check the wiring to the TPS again.

The car seems much faster now (and uses more fuel!). Had one or two opportunites to put my foot to the floor on today's commute      

Rory's Dad

[mef]

Hi Martin,

It's great to hear that you finally got it sorted but as far as I'm concerned it's still a complete mystery as to what was wrong as you've not said what the guy did other than a "complete remap".

Why did it need a complete remap? What specifically was wrong with the original map (did you put your original map back in after having the TB's in bits?)

When I came over, as you know I ended up ADDING 50% fuel over the whole map to make it run better than it was, also 20degree extra advance over the whole map. So If you had inadvertantly fixed an air leak during your work the map would obviously be completely wrong. If you remember I stored your original map on your memory stick.

If you remember I did question those SBD aftermarket replacement injectors, I'm still suspicious about them being equivalent to the original 744's that were in the original stolen TB's and they are the only part that has been changed from the original spec.

Regarding all the comments and suggestions above in this thread, yes I tried all these things to no avail. The DTA software was showing everything as correct and sensible. I even tried a well proven base map just in case your map had somehow got corrupted (this can happen with DTA E48's) although how someone stealing the TB's could corrupt a map I'm not sure! The engine wouldn't run at all with the VX base map which was also very strange as that map was the base that was used by Leon Boutell originally and it usually works any XE on TB's. (it's supplied on the DTA software CD)

So, can you find out some proper info as to what exactly the guy found and did to fix it, I'm very interested to know as it was very frustrating for me not being able to make more progress with it during the several hours I was there!

Cheers,

Martin Fox