View Full Version : 4age 20V problem
here is the problem MT8 microtech computer on 20v. New loom professionally made and has been off the car twice and checked. The car gets to 5000 on the road and dies. Will rev to 7800 on the dyno running TPS and has just spent 7 hours being retuned on the dyno. Put it on the road and it dies! Things replaced so far are computer, all sensors twice, injectors serviced, dizzy replaced from working car, fuel pump and filter.
Looking at hand programmer, on the road gets to 500 and injectors suddenly read 0, and feels like rpm cutout. Replacing computer does not change things and this did not occur on the dyno, computer has been checked. Owner is upset and willing to offer a reward (seriously) for a solution
30-10-02, 09:36 PM
You've no doubt though of it & tried it, but are all the appropriate earths in pace and definitely working?
I had a similar problem running a Haltech. As Bill said, check the Earths, also check the Spark Plug leads, Spark Plugs and coil(s)
Mine ended up being a plug lead and it would only occur at 3/4 to full throttle at about 5600rpm
What type of dyno were you using, and when it revved to 7800 was it at full load or a partial load
31-10-02, 01:24 PM
Change the Plug Leads, they will be interfearing with the computer, i would throw a set of magnacore leads on there, if you want to try some other leads the cheap top guns will work ok till about 8000 rpm.
Also check that the loom is joined properly to the injectors and there is no chance that the 2 wires can touch.
Thanks for the suggestions, I will pass them on. Dyno was a rolling road, with full mapping carried out. gave 128bhp at wheels on full load. All components have been given their own earths and these have been checked. I have a set of magnacore leads spare so will try them. But why ok on the dyno and a dog on the road. Interestingly it can on rare occasions be worked through by backing off and blipping the throttle, but is very inconsistent.
plug leads changed...no difference with magnacore or new std. Ideas, reward offered is over $100
I am assuming that you are yousing the stock CAS on the Exhaust Cam? Does the Microtech have the ability to adjust gain settings on the home and trigger? You may be getting an erroneous home signal due to too high a gain. the problem you are having sounds exactly the same as the one I was having 18 months ago with mine. We ended up trialling different home and trigger gain settings to find a setting that was stable (gives a constant RPM) at cranking as well as at high RPM. It was a little time consuming (being on a race track, car is not registered)but we ended up with the home gain set as low as we could while still getting a reliable signal.
128hp at the wheels? What setup are you running (stock, extractors etc) Thats a pretty health figure. Max I could get was 70Kw at the wheels after 2 days on the dyno, running Avgas and a custom set of 4-2-1 extractors, otherwise stock.
Also, what other details can you supply about your fuel system? are you running a surge tank? what type of fuel pump? Do you have any way of monitoring fuel pressure on the road?
I am interested to hear what has been done to the 20v as well :D
20v is stock apart from intake prior to TB's, was a very low KM engine apparantly. Goes through either a CR or std box depending on the use. Fuel system is bosche pump in tank, to fuel res, through rail with return line. Same system running on 3 other cars with no problems. The difficulty I have is with the dyno fine/crap on the road (with NO changes between)(by the way this is not my car)
I queried fuel fluctuations and filter is due to be changed (its the only thing that hasn't been changed according to the owner), but don't know why the injectors read 0 at 5-5500 on the road and not on the dyno?!
I will pass on the CAS idea and see what happens.
02-11-02, 08:37 PM
Just another thought, did you specifiy when you ordered the computer that it was for a 20v not a 16v?? if it is a 16v computer you will have problems
Originally posted by Nero
20v is stock apart from intake prior to TB's.
Out of curiosity, what do you have before the throttle bodies?
I know that this is one place to make some cheap power, and am interested to see what you have done.
10 sec the computer was one of purchased at the same time as a job lot, all were for 20v. The perplexing still remains, why ok on the dyno and not on the road?
Taylz, I believe its a custom airbox, more for bonnet clearance issues in the clubman
06-11-02, 08:14 AM
Hmm it is a interesting problem,
my car had the same problem, on the dyno perfect, on the stree/strip would miss its ass off when i changed gears hard, if i changed soft it would be fine,
what plugs is he running?? where is the comptuer mounted?? near and electrical devices?? msd etc?? coils??
what are the mixtures doing when it misses??
Originally posted by Nero
Fuel system is bosche pump in tank, to fuel res, through rail with return line.
So you are saying you have a High Pressure pump in the tank, feeding a surge tank , then a line from the surge tank to the rail, and a return line.
Describe your fuel res. Is it like a short wide canister or a skinny tall tube. Where are the pickups?
Starting to get a bit of a long shot, but if it is in a clubman and the other cars are heavier, then the clubman will accellerate a lot harder, and hence fuel surge would be more of a problem. I would think that a better fuel system would have a feeder pump in the tank and the high pressure pump on the line to the fuel rail. Also, where does the return line feed back to - the main tank or the surge tank? I have mine running to the surge tank with an overflow running back from the top of the surge to the main tank.
What sort of pull are you running on the dyno. If it is a straight full load pull in say 4th gear from low revs to redline it'd only last a few seconds. If you are simulating going up through the gears it'd still only last for say 20 seconds. maybe on the road because you are constantly running, your fuel rail isn't getting the feed from the surgetank that it requires.
What length trumpets is he running on the throttles, or is he running the stock trumpets?
I can see why your friend is getting frustrated... Good luck
09-11-02, 04:38 PM
Just another random brain fart - I had a mate of mine who had a Golf 1600cc engine destroked to 1300cc for the Sports 1300 class, and his engine would run fine on the engine dyno, but overheat like a bugger on the track. Similar complaint in that the set-up on the dyno was exactly the same as it was on the car.
Turned out the problem was that the radiator inlet hose was being crimped over by the bonnet (just!) when in the car, and so when the water flow built up it was sucking the pipe flat and cutting off the flow of water.
Soooo ..... just wondering is there's any flexible rubber pipes in the air inlet system that might be slightly squashed when in the car and not on the dyno, so when the engine is sucked air hard on the road the pipe is collapsing and shutting the engine down .... ?
sorry for the lack of reply...been yoalding in the porce'n trumpet for a few days...thats what you get when working with kids!
Bill the rad runs are all ali tube apart for a small section of rubber.
Tayls as far as I know the surge tank is a tall one about the size of 1 1/2 coke cans with the feed in the top and the outlet down the bottom. Any help? Re the trumpets, I'm making a set of f'glass trumpets with an airbox for these guys (in exchange for them doing a job for me) so this will change in the nearing future.
10sec it turns out he is running different plugs, will sort this out. Still difficult to point to this and say it would make the diff dyno/road though.
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