[Damo]

OK, so my G16'd Sierra is running OK, but there is something that is bugging me.

On light throttle openings (eg, cruising at 60 in 4th) it will seem to go back to idle without any movement of the throttle. That causes and on/off of power that is REALLY annoying. I had the TPS off the throttle body when I had everything pulled apart, i'm thinking I need to set that up properly.

Any ideas?

[royce]

I think my tps is out and gives it a friggen annoying stutter when you are rolling in traffic and accelerate from about 1500rpm

if you free rev it to 3000rpm for a bit and let off the throttle does it drop back to idle or stuff around for a bit? sounds like thats what its doing, mine was doing that from air leaks anda dirty throttle body

easy way to fix it was unplug the air idle valve

[Damo]

royce wrote:

I think my tps is out and gives it a friggen annoying stutter when you are rolling in traffic and accelerate from about 1500rpm

Mine does something like that. When I nail it, it hesitates for a half second then goes.

royce wrote:

if you free rev it to 3000rpm for a bit and let off the throttle does it drop back to idle or stuff around for a bit? sounds like thats what its doing, mine was doing that from air leaks anda dirty throttle body

easy way to fix it was unplug the air idle valve

I dont think mine does that, but I can try it. Idle is fine so i'm not sure it's air leaks. I haven't replaced ALL the vacuum hoses though.

[royce]

mine idled fine but would sit on 1500rpm for about 3 seconds before dropping back to idle when you got off the throttle, for some reason fixing the leaks and the throttle body fixed it

[Damo]

According to a PDF I have the voltage at the ECU for the TPS is 0 at idle and 3 - 5 with the throttle open. I think I have the TPS adjust so that at my problem throttle opening it's right on the 0/3 volt threshold. That's my theory anyway.

If I can figure out which wires to put my meter on I should be able to adjust it so that it's reading 0 volts at idle. I can at least then discount the TPS setting as part of the problem.

[royce]

from memory its easy enough to figure cause there is only signal, power and earth on the tps

[Damo]

royce wrote:

from memory its easy enough to figure cause there is only signal, power and earth on the tps

I'm sure my TPS is a 4-wire job. Just looking at that doco again and I have made a mistake. Those voltage readings are for the "TPS idle switch", so that may be the 4th wire.

The TPS signal itself should read 0.5 - 1.2V fully closed and 3.4 - 4.7V fully open.

[royce]

yeah thats what I meant

[Damo]

I made a quick adjustment on the TPS before I left for work. It's heaps better

[Hybrid]

This probably isn't what you want to hear Damo but putting your MS on this thing would probably speed up the 'bug fixing' stage of the build. I mean at the moment your trying to make an existing system work in a new vehicle. Whereas with the MS you've got all the components and its just a step by step set up..... (although mines still stumbling off idle)

[Damo]

Hybrid wrote:

This probably isn't what you want to hear Damo but putting your MS on this thing would probably speed up the 'bug fixing' stage of the build. I mean at the moment your trying to make an existing system work in a new vehicle. Whereas with the MS you've got all the components and its just a step by step set up..... (although mines still stumbling off idle)

Yeah I know, I was thinking yesterday that setting the TPS would be so easy with the MS hooked up.

On the up side I should be able to keep the stock ECU in the car and just swap it over if I have any problems with the MS.

[royce]

can you come adjust mine for me? I'll leave the bonnet open

I think its better to sort all this out now then fit the MS, then you know any problems arent likely to be from a faulty sensor and so on

[Hybrid]

If the engine wasn't running at all I would agree but the benefit of the MS is that its all on screen. You can see which sensors are out. TPS would have been easy for instance. Its calibrated for the computation by closing the throttle and getting a reference point then opening it and getting one. Or if the IAT sensor is showing 90 degrees you know its off and so on and so on. I've just found things like a faulty IAT that on the voltmeter appears fine but has faulty spikes through the resistance range. I only picked these out on the MS logs. I think Damos got the best idea with building a loom that allows interchange between the stock and ms ecu.

[Bruce]

God I'm glad you guys know what ya talkin about
If I have a prob I just yell "ROYCEEEEEEEEEEEEEE"

[royce]

any luck Damo will like the stock ECO so much he sells me the MS for $50

[Hybrid]

Hehe. Buy the kit for like $170 then get Damo to build it for ya. At least then it will be fresh and will have never been tainted by running a poxy 1.3L lol

[Damo]

Hybrid wrote:

Hehe. Buy the kit for like $170 then get Damo to build it for ya. At least then it will be fresh and will have never been tainted by running a poxy 1.3L lol

Yeah, and you can get a version 3.0, mine is a 2.2. They do much the same thing, the 3.0 has a few improvements though.