bidderman1969
detailer
personally i'd try one thing at a time as these things tend to work together, so if ones out its easier to eliminate i would imagine
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JR
Old enough to know better
pretty sure that's what i did, i'll try it again anyway. Nothing has suddenly made the thing idle smooth and i've been trying alot of ways/ unplugging the various sensors
The noise i mentioned stops upon depressing the clutch pedal so may not be related.
the ecu or something on that side makes a click at the low ebb of the bounce.
When i was in the garage getting the uno mot'd the mechanic said he'd first look at the air pipes if the idle is doing that...
The noise i mentioned stops upon depressing the clutch pedal so may not be related.
the ecu or something on that side makes a click at the low ebb of the bounce.
When i was in the garage getting the uno mot'd the mechanic said he'd first look at the air pipes if the idle is doing that...
Chris H
master of boobies
if you attached the CTS upside down you would have had to smash the wiring plug to do so.
the click is the charcoal canister solenoid it will do this on a surging idle.
The ICV is not the problem the problem is the lambda or the cts entering closed loop to early and as a result the lambda is coated in crap thats not getting removed as its not getting hot enough.
If you unplug the lambda it will stop but your better sorting the issue, so pull the lambda out and blowtorch it. Or get the engine hot hot and go for a rag, by a rag 50 - 60 miles at high speed.
An air leak wouldn't cause the idle to surge up and down unless you were opening and closing the leak constantly.
The real issue is the lambda sensors heater has most likely stopped working, the heat shield on the exhaust downpipe is most likely missing and the location of the lambda is miles away from the required heat. Of course if there has been a head gasket leak or it burns oil then its got no chance anyway.
the click is the charcoal canister solenoid it will do this on a surging idle.
The ICV is not the problem the problem is the lambda or the cts entering closed loop to early and as a result the lambda is coated in crap thats not getting removed as its not getting hot enough.
If you unplug the lambda it will stop but your better sorting the issue, so pull the lambda out and blowtorch it. Or get the engine hot hot and go for a rag, by a rag 50 - 60 miles at high speed.
An air leak wouldn't cause the idle to surge up and down unless you were opening and closing the leak constantly.
The real issue is the lambda sensors heater has most likely stopped working, the heat shield on the exhaust downpipe is most likely missing and the location of the lambda is miles away from the required heat. Of course if there has been a head gasket leak or it burns oil then its got no chance anyway.
JR
Old enough to know better
unplugged the lambda and drove about 30 miles - no change.
Thanks for explaining the click
Going to have it out and buy a blow torch also going to test the new and old cts as per tech article. I want to take off the cat and hollow it out for a sort of straight throuh any how, wether it'll com off and go back on readily is another question.
The car does burn a little oil, not too sure about the head gasket. I'll check for the heatshield too. From the service history the neither gasket or lambda been changed.
Thing is it idled fine before it came off the road for the winter/ cam belt change
Thanks for explaining the click
Going to have it out and buy a blow torch also going to test the new and old cts as per tech article. I want to take off the cat and hollow it out for a sort of straight throuh any how, wether it'll com off and go back on readily is another question.
The car does burn a little oil, not too sure about the head gasket. I'll check for the heatshield too. From the service history the neither gasket or lambda been changed.
Thing is it idled fine before it came off the road for the winter/ cam belt change
JR
Old enough to know better
yes mate the 3 pin plug that is at the back of the subframe on the o/s, did not change the idle problem. I've left it unplugged for now.
Will a new one likely cure the issue, i don't know. I won't either till next month as funds are tight this one. probably won't be driving th 19 at all as i can't even fill the tank
Will a new one likely cure the issue, i don't know. I won't either till next month as funds are tight this one. probably won't be driving th 19 at all as i can't even fill the tank
tracklogic
Membre
The lambda sensor is one of the main inputs to the ecu when its running closed loop, the other two are the flywheel sensor (VR sensor) and the MAP sensor. All the other sensors are just used to trim the AFR from stoich, for example if the engines cold then you need < 14.7:1 with slightly different ignition advance as the fuel won't burn the same as when the engine is up to optimum temperature.
So as Chris said, get yourself a new (for £30 no real point getting a second hand o2 sensor, they have a hard life sat in the extremely hot exhaust gas stream) O2 sensor, you won't look back. Coolant sensor is easy enough to check, the ohm readings are listed in the haynes manual so you can shove a multimeter on the terminals and see that your somewhere in the ball park. Idle valve, these tend to stick, give them a clean out with some carb cleaner, but i doubt thats causing the issue.
So as Chris said, get yourself a new (for £30 no real point getting a second hand o2 sensor, they have a hard life sat in the extremely hot exhaust gas stream) O2 sensor, you won't look back. Coolant sensor is easy enough to check, the ohm readings are listed in the haynes manual so you can shove a multimeter on the terminals and see that your somewhere in the ball park. Idle valve, these tend to stick, give them a clean out with some carb cleaner, but i doubt thats causing the issue.
tracklogic
Membre
MAP sensor is easy enough to check if you've got a vacuum pump, alternatively you could use the engine as a vacuum source.
At idle you should be about ~35kPA of vacuum (so with the throttle plate shut) - measure the voltage on the back of the plug for the MAP sensor, then as you slowly open the throttle plate the voltage should start to increase until at wide open throttle it should be at its maximum (if i remember correctly the voltage increases as the vacuum decreases - i.e you'll get a low (this is just a random number so dont use it as gospel) 0.5v @ 35kPA and something like 4.5v @ 101kPA (which is wide open throttle - as its atmospheric the engine cant create any vacuum due to the throttle plate being fully open).
<hard sell> Alternatively if you invest in one of my shiny usb diag boxes you'd be able to graph your MAP sensor output vs engine RPM vs throttle position and see if it was responding correctly
Same for the lambda (O2) sensor btw as well... you should be able to graph its output and see that its not responsive! </hard sell>
Matt
At idle you should be about ~35kPA of vacuum (so with the throttle plate shut) - measure the voltage on the back of the plug for the MAP sensor, then as you slowly open the throttle plate the voltage should start to increase until at wide open throttle it should be at its maximum (if i remember correctly the voltage increases as the vacuum decreases - i.e you'll get a low (this is just a random number so dont use it as gospel) 0.5v @ 35kPA and something like 4.5v @ 101kPA (which is wide open throttle - as its atmospheric the engine cant create any vacuum due to the throttle plate being fully open).
<hard sell> Alternatively if you invest in one of my shiny usb diag boxes you'd be able to graph your MAP sensor output vs engine RPM vs throttle position and see if it was responding correctly
Same for the lambda (O2) sensor btw as well... you should be able to graph its output and see that its not responsive! </hard sell>Matt
Last edited by a moderator:
lewis77
Active Member
MAP sensor is easy enough to check if you've got a vacuum pump, alternatively you could use the engine as a vacuum source.
At idle you should be about ~35kPA of vacuum (so with the throttle plate shut) - measure the voltage on the back of the plug for the MAP sensor, then as you slowly open the throttle plate the voltage should start to increase until at wide open throttle it should be at its maximum (if i remember correctly the voltage increases as the vacuum decreases - i.e you'll get a low (this is just a random number so dont use it as gospel) 0.5v @ 35kPA and something like 4.5v @ 101kPA (which is wide open throttle - as its atmospheric the engine cant create any vacuum due to the throttle plate being fully open).
<hard sell> Alternatively if you invest in one of my shiny usb diag boxes you'd be able to graph your MAP sensor output vs engine RPM vs throttle position and see if it was responding correctly
Matt
Cheers Matt, I'll check that later. Although I think it wouldn't be just this as the MAP isn't temperature dependant :?
<hard buy> I'll take one as soon as you can ship one
</hard buy>
