Soarer Central: V8 driving like a tractor upto 3000RPM

Soarer Central Mechanical - Common V8 driving like a tractor upto 3000RPM

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Charlie Hooper
TryHard
Queensland
V8 Limited Soarer

Posts: 152
Reg: 10-2005

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Thursday, December 29, 2005 - 07:11 pm, by: Charlie Hooper (Charlie)

I was just at the shops and come back to the car to go home but it wouldn't start. I opened the bonnet and checked the terminals, one was loose and sparked when I twisted it so I tightened it up a bit and the car started fine.

I reversed out and went to drive off but the car sounded and went about as fast as an old tractor. I got out on the street and found it did it upto 3000RPM.

My clock reset to 1:00 so I'm guessing the ECU may have reset, I have a screwed air/water temp sensor (waiting on Tuff Toys to find me a replacement.. for around a month now) so my question is, is the ECU trying to re-learn and going "OMG OMG THERE'S NO AIR, LETS PUT AS MUCH AIR IN AS POSSIBLE" then when it hits around 3000rpm it's starting to be at a rev range where it can use a lot of air and is putting more fuel in if you get what I mean? Or is something just screwed?

Cheers

Alan Carter
TryHard
Vic
V8 UZZ31

Posts: 120
Reg: 07-2005

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Thursday, December 29, 2005 - 07:49 pm, by: Alan Carter (Alky)

If the clock has reset itself, I'd be checking the battery terminals and/or the earth connections.

Meanwhile, I have a paddock that needs plowing.....

Jeff Harper
Trader
NSW
UZZ32 Active V8

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Thursday, December 29, 2005 - 07:50 pm, by: Jeff Harper (Jeffh)

1/ Why would your car SUDDENLY react like that to a bad sensor if it's been bad for a while. ie, I don't think so.

2/ Your HT lead was loose.... why, have you been fiddling? C'mon, tell us the truth!

3/ Didn't wash your engine bay recently did you?

Mark Paddick
Goo Roo
ACT
Soarer UZZ31

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Thursday, December 29, 2005 - 08:30 pm, by: Mark Paddick (Sparks)

Temp sensors can be replaced with a fixed resistor temporarily (see recent thread for appropriate values).
The only sensors that are disregarded by the ECU when revs increase are the knock sensors (there are two under the intake manifold and they are $180 each...sorry) so that would be my best guess. The ECU doesn't ignore knock sensors until about 4500 rpm though....
Resetting the ECU does not normally have such a dramatic effect on V8s but the fact that it has reset points to battery and/or terminals.

Charlie Hooper
TryHard
Queensland
V8 Limited Soarer

Posts: 154
Reg: 10-2005

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Thursday, December 29, 2005 - 08:31 pm, by: Charlie Hooper (Charlie)

It only started doing it (the slow/loud driving) after the battery terminal had lost a good contact (probably crap built up in there) which caused the clock to reset so I was assuming the ECU as well..

Before hand the sensor was just making it surge from time to time...

What's a HT lead?

And no I haven't washed the engine bay recently but I did go through an auto wash. I didn't notice any water coming from below though.

The problem only started happening straight after the terminal had lost a good contact and I made it contact better and started the car.

BTW, thanks for the replys guys.. Keep em coming :D

Mark Paddick
Goo Roo
ACT
Soarer UZZ31

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Thursday, December 29, 2005 - 08:37 pm, by: Mark Paddick (Sparks)

First thing to try is a deliberate reset. The faulty battery connection may not have disconnected long enough for a proper reset. Disconnect battery for a few minutes (and clean all the terminals while you're at it).
Don't forget that batteries are prone to intermittent behaviour as they age; internal inter-cell connections crack and become intermittent so try another good battery if you can.
HT (High Tension) lead; from coil to distributor (there are two of each). This is a likely cause of such a problem. Once revs rise and spark voltage increases small breaks or loose connections in ignition HT wiring are easily jumped by the spark and the problem goes away.
I have seen a few faulty ECUs lately too...

Charlie Hooper
TryHard
Queensland
V8 Limited Soarer

Posts: 155
Reg: 10-2005

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Thursday, December 29, 2005 - 08:51 pm, by: Charlie Hooper (Charlie)

Yeah, I'll try the re-set tomorrow. I'm leaning away from something else braking at the exact moment the battery terminal broke connection though.. Here's hoping heh

Cheers for the reply

Mark Paddick wrote on Thursday, December 29, 2005 - 08:37 pm:
First thing to try is a deliberate reset. The faulty battery connection may not have disconnected long enough for a proper reset. Disconnect battery for a few minutes (and clean all the terminals while you're at it).
Don't forget that batteries are prone to intermittent behaviour as they age; internal inter-cell connections crack and become intermittent so try another good battery if you can.
HT (High Tension) lead; from coil to distributor (there are two of each). This is a likely cause of such a problem. Once revs rise and spark voltage increases small breaks or loose connections in ignition HT wiring are easily jumped by the spark and the problem goes away.
I have seen a few faulty ECUs lately too...