Sorry not sure why it double posted....

Craig.

[Edited by Catalunya 051 - 11/4/2003 5:46:29 PM]

 

My defi boost gauge registers in 4th and 5th approx 1.35/4 bar on full chat and quickly holds 1.2 bar....should i be worried?

 

Does the engine cut out? If not, then I would simply watch th gauges. If it was overboosting too far the engine management system would start the "fuel cut" syndrone, so warning you of this.

 

Sorry to gate crash, but could you describe the Fuel cut effects?

The reason I ask is that late the other night (cold and moist conditions) I came down a local dual carriegeway at a good speed (ton+) for a bit (the car felt normal) then turned down a winding b road with a straight that goes up a hill which I took in fourth with foot down going from around 3000-5000rpm during which I noticed the acceleration was easing off then coming back at around 1 sec intervals. It's not done it since (or I can't re-create conditions). The only other symptom of problems is the tickover currently drops after ~20seconds to less than 800rpm and goes pretty lumpy. Lastly, on looking under the bonnet I heard a sucking noise and found the cap missing from the tap off point on the top of the inlet manifold (front right hand side of the coil pack). I have put a bit of folded over tubing, cable tied in place, to seal this and the tickover is much more stable. Is this related to the power surges? The car is a MY97 with WRSport back box and Ram Air panel filter (otherwise standard) normaly running on Optimax but at the time of the surges it had Sainsbury's Super Unleaded in the tank.

Thanks for letting me but in

Craig.

 

Depends how it is mapped if it is mapped.

You can easily det and make a hole in a piston with this sort of overboost if the timing or fuelling are not setup for it, fuel cut will not necessarily save you. Otherwise, Scooby engines would never die from overboost related detonation.

 

Craig, worth telling if it is boost related by looking at a boost gauge.

 

I don't have a boost gauge, just standard UK engine so assumed it shouldn't need worrying about! Scoob gives such consistantly reliable performance normaly, that I didn't bother with the cost and hassle of fitting one!

 

Time to bother now if you still have a problem.

 

OK, it certainly felt like it was coming in and out of boost, going back to my first question, is this what the fuel cut feels like or does it feel more like hitting the rev limiter?

 

Go to 5000 RPM in 2nd gear on full throttle and then lift off the throttle as quickly as you can. That feels like fuel cut.

 

It happened to me the other day powering up then pop total loss of power for half a second or less creating a nasty jerk
NOT NICE!!!

I called my tuners who told me what it was and not to be too worried as I do have mods and it's a built in saftey measure in the car, hope it works!

 

Yeah, so long as you're not overtaking/pulling out/cornering hard the next time it happens... Potential accident waiting to happen. Also bear in mind the points JB has made.

Regards,

Ade.

 

ty The judge

 

Catalunya 051

I had exactly the same problem which Pat (Scoobysport's/Xtreme's mapper) sorted quickly after a check of what was happening.

It (MY99 UK + Ecutek + decat) was overboosting to 1.5 bar then the ECU was dragging it back and so on in cycles. The boost target was 1.25 bar. It never hit fuel cut though.

Sorted by a slightly larger restrictor and has been behaving ever since.

 

Thanks for that Soapy Sam, that sounds just like my "anomaly". I think it was all to do with: Crap fuel, a long flat out boost in high gear preceeding the observed problem, cool damp conditions and the blanking cap missing from the unused inlet manifold tube attachment point (does anyone know what this is for??).

It seemed like the ECU was getting confused by the un-accounted for "extra" air getting in and was trying to compensate which resulted in the minor/gentle power fluctuation.