Thursday, May 28, 2009 - 12:01 am, by: Andrew Duaso(Andrewd)
I've done a search on this but my car seems to have a different problem
when it's up to temp the car is very sluggish off the line untill 4000rpm where it really takes off... it's like an old crappy V8 till then then @ approx 4000rpm the turbo's spool up or the Vtec kicks in YO! well not really but thats what it's like
for example when the engine is warm it cant even do a burnout (foot on brake/accelerator, let alone spin off the line on take off) yet when engine is cold it can
also the power loss is below 4000rpm only when engine is at operating temp, above 4000rpm it goes hard cold or warm
what can i do? car is stock other than 2deg advanced cams, dont know why but the mechanic told me they are, and a half ass exhaust system and bfi, still on std cats (untill next week)
will a unichip or similar fix this problem or is it the ecu?
other than that the car is running fine sucks the juice around town, but it's probably they way it's used (short trips carrying load etc..) and 10L/100km highway
engine pulls smoothly to the redline runs well only issue is occasional erratic idle due to the isc which is getting replaced
Thursday, May 28, 2009 - 12:37 am, by: Steve Zac(Tnt992)
I had the same issue, apparently the on board computer tracks up to 11 takeoffs and makes the car drive accordingly. Don't quote me what I have been told is just what I am saying. If I always drive rough the car goes well.
Thursday, May 28, 2009 - 09:02 am, by: Tim Appleton(Timbo)
I have a similar thing happen with my car. The problem is most likely that the car is running lean possibly because of the exhaust. Once you hit around 4000rpm then the ECU richens things up again and you blast off into the sunset.
I have run a wideband oxygen sensor on my car and it tends to run extremely lean up until about 4000rpm, as well as the factory oxygen sensors showing a lean signal.
It's possible that it could be caused by an old ECU with dodgy caps. It's only a possibility as I haven't had a repaired ECU running on my car to test. A unichip or any other suitable fuel tuning piggyback should fix this as you can have it richened up in the lower rev range at WOT. A suitable fuel tuning piggyback will have to be able to alter a frequency signal.
Thursday, May 28, 2009 - 07:41 pm, by: Andrew Duaso(Andrewd)
thanks for the help
it's going back to the mechanic next week for something else, i'll get him to checkout the engine ecu, as that seems most likley... everything else was done when i got it only a few thou ago, such as plugs leads belts and so on....
i dont thrash it, but i just want it to be in top condition like new... it goes well, but it does suck that when you need to get a quick get away from the lights for whatever reason nothing happens till 50km/h ish
Friday, May 29, 2009 - 05:09 pm, by: Sean Routledge(Stircrazy)
Andrew, Have you boxed your BFI in properly? Maybe when the engine is warm you're sucking in all of the hot air from it? Then at 4000rpm you're moving fast enough to create a flow of cooler air? That was my diagnosis on my car anyway.
Joe Russell TryHard Marlborough 4.0 V8 GT-L(UZZ31)
Saturday, May 30, 2009 - 05:28 pm, by: Joe Russell(Joe_r)
Maybe that Sean-I once got a 5sec standing 100 after driving to town(about 15kms), then tried again straight after and it was like the throttle was at half cock, and it was 7sec flat. 5sec has never come again, although I haven't put the car in that situation again. My friend was timing and we both noticed a full lack of pull, until the rev's were up.
Maybe its the Trans?
However Andrew, ECU definitely has to do with this situation, my cars exactly the same except has a cold starting issue...
Saturday, May 30, 2009 - 05:45 pm, by: Rob Rojo(Rob_tt)
Check your intake and water temp sensors, if its running well when cold that would be the first place I would be looking. If not as Joe mentioned swap the ECU.
Saturday, May 30, 2009 - 07:02 pm, by: Sean Routledge(Stircrazy)
But I thought all cars run better when they're cold? Every car i've had has run better first thing in the morning. (Though I try to keep it under 2000RPM till warm.)
Saturday, May 30, 2009 - 07:31 pm, by: Rob Rojo(Rob_tt)
Cars usually run better in the morning or late a night because the air is colder, a cooler engine will run better than a hot engine but the ECU senses engine temp and will run richer and alters the timing till its up to safe operating temp so it will probably be down on power till then.
Saturday, May 30, 2009 - 08:04 pm, by: Andrew Duaso(Andrewd)
it appears to be a running rich issue, or lean i should say when warm
yes most cars go better when ambient temps are low, but in this case it's not the ambient temps or airintake for that matter...
it's running lean down low then @ 3500rpm to be more precise it pings slightly then after that it runs a tad rich...
it also seems that an aftermarket piggyback thing will help, but i'd like to get the actual ecu sorted then worry about a piggyback.... unless im better off with the piggyback... i dont know maybe the factory ecy dosent need to be repaired if the piggyback tels the car what to do.... an i on the right track?
Sunday, May 31, 2009 - 04:22 pm, by: Mike Beck(Gold_40gt)
Unplug your AFM, see if that makes any performance change down low...
It goes to a fixed preset A/F setting richer than normal.
If it's considerably more powerful down low then your AFM could be playing up, might pay to test it with an ohm meter if that is the case.
Also....... try another ECU as yours might have some issues because of age, the capcitors tend to leak over time, dry joints form etc resulting in bad performance - from what I remember it seems to be a down low problem.
It's definitely electrical / fuel related I would say.
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