spi injection fault

[mk1morris]

i have a 1996 spi its runs fine then all of a sudden it will pick up reves and idle at aprox 1500 then drop to about 600 then die it starts back up fine then idels aprox 1000 then jumps to 1500 then drops and dies again any ideas anyone

[monkeyjim]

These need to be kept spot on .
Check all the basics are ok as you would a carburettor car . check all vacuum pipes and the right angled ends are connected and in good condition , any splits then replace . Check condition of all wiring and connections .

This is the basic of modern car fault finding and the sort of thing we do at work before we start delving into diagnostic work and scanners .
Even the wrong grade or low oil can cause a misfire on a modern car so its wise to check even the most basic things before wasting hours and hours to find its a pipe off , blown , fuse , bad plugs or low engine oil .

So check all basics and then call Shawn , reckon he still has the diagnostic kit.

[Stephen]

I wouldn't want to second guess, agree with everything Dave said. But if it's a problem just at idle, it could well be a problem with the stepper motor. They often skip steps causing an erratic idle speed

[mk1morris]

thanks guys so far i hane checked all sensors i can see and used a eletrical cleaner tod\ay im goin to cheak all vacumes is there a way off cheaking the steper
if this fails ive been told it could be the ecu

[Miniböttcher]

i know that my parents have had the same kd of problem with there cavalier, drives fine, then idle holds high then dies.

its down to only doing short jounery, and they drive it very softly,so it does not get a god clean out,
the idle control valve on the vauxhall gets clogged up and sticks etc

we just give it a good clean out, we found a few pipes that had a odd splits and were damaged and replaced, and i gave it a bet of a welly down the bypass to blow it out.

give it a service, and what dave said before, check every connector pipes etc,

dave has old me in the past if my parents car keeps messing about, ( quick fix) take air box off, carb cleaner, full throttle spray down the intake, it will start to die but it gives it a good clean out

[mk1morris]

thanks guys pulled all vacum pipes etc off inspected them and found a big split in the one that rus fom manifold to the map sensor replaced the pipe checked the one that runs to the ecu and now its all good. thanks ant for all your help today

[monkeyjim]

Unfortunately a ecu fault is one of the first things someone says is the prob , as you have found out it can be so simple .