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Guess what?? another renix low rough idle.
- Thread starter AKghandi
- Start date
well I havent changed anything yet. but i am now getting an occasional normal idle!
its not constant like if i rev the engine a bit it will go back down but its progress.
also i cant seem to get any movement from the EGR doing the throttle blip test.
the solenoid seems to work. when i unhook it i get vacuum and when i re hook it i get no vacuum.
also bit of random yesterday i forgot to hook the cts and O@ back up after i got the manifold switched..
then while they were unhooked i unplugged the MAT to plug in the other MAT i located in the intake tube. and the truck almost died..
thats stange because it should have been in open loop right?
its not constant like if i rev the engine a bit it will go back down but its progress.
also i cant seem to get any movement from the EGR doing the throttle blip test.
the solenoid seems to work. when i unhook it i get vacuum and when i re hook it i get no vacuum.
also bit of random yesterday i forgot to hook the cts and O@ back up after i got the manifold switched..
then while they were unhooked i unplugged the MAT to plug in the other MAT i located in the intake tube. and the truck almost died..
thats stange because it should have been in open loop right?
Well after driving the truck for about 70 miles, I can say I have a mostly normal idle now!
Not really sure what fixed this, but its alot better.
I should note that I relocated my spare MAT to the intake tube. Not sure if that helped or not yet.
I will say I have noticed a good gain in power. chugging around town in 4th at 1250 I can accelerate without downshifting. its no rocket but it actually does it.
at 2000 rpm in 3rd on the highway I can accelerate pretty dang good without downshifting. both in "Comfort" mode
That may be from the cold cold air intake and the MAT reading cooler air.
The truck is running cooler but that may just be from the weather.
Its overall a much smoother happier truck with the EGR system intact.
Still not sure if everything is working like it should but it seems to be. still cant get the EGR to move with the throttle blip test at Op temp.
Getting vac to solenoid and the EGR moves and isn't leaking. maybe it just moves very slowly? I did notice that not alot of vacuum comes out of the solenoid.
Not really sure what fixed this, but its alot better.
I should note that I relocated my spare MAT to the intake tube. Not sure if that helped or not yet.
I will say I have noticed a good gain in power. chugging around town in 4th at 1250 I can accelerate without downshifting. its no rocket but it actually does it.
at 2000 rpm in 3rd on the highway I can accelerate pretty dang good without downshifting. both in "Comfort" mode
That may be from the cold cold air intake and the MAT reading cooler air.
The truck is running cooler but that may just be from the weather.
Its overall a much smoother happier truck with the EGR system intact.
Still not sure if everything is working like it should but it seems to be. still cant get the EGR to move with the throttle blip test at Op temp.
Getting vac to solenoid and the EGR moves and isn't leaking. maybe it just moves very slowly? I did notice that not alot of vacuum comes out of the solenoid.
- Location
- MilkyWay Galaxy
The MAT data and MAP data and I think the CTS data are used all the time, open or closed loop. The O2 sensor data is the key extra data set for closed loop.
I hope any work you did on manifold gasket swaps included checking the manifold sealing surface for true flatness? I had to mill and patch mine on the exhaust and pray I did over do it since the two manifolds use the same bolts and washers......
Also the MAT is located in the intake manifold for a very good reason as the manifold heats and thins the air changing the air density that is used by the ECM to calculate the O2 and air feed rate density. It needs to be in the manifold to get the right temp data to the ECM.
I hope any work you did on manifold gasket swaps included checking the manifold sealing surface for true flatness? I had to mill and patch mine on the exhaust and pray I did over do it since the two manifolds use the same bolts and washers......
Also the MAT is located in the intake manifold for a very good reason as the manifold heats and thins the air changing the air density that is used by the ECM to calculate the O2 and air feed rate density. It needs to be in the manifold to get the right temp data to the ECM.
- Location
- MilkyWay Galaxy
"That may be from the cold cold air intake and the MAT reading cooler air.
The truck is running cooler but that may just be from the weather"
In that case I think you found the cause of the low idle, a bad MAT or a problem with the intake manifold temperature where the MAT mounts (an exhaust leak blowing on it there? But that is a real stretch though).
The MAT needs to react fast to air flow rate changes, and any dirt or oil or soil on it will make it slow to respond. But at idle the air flow rate should be pretty steady, so ..... That leaves an MAT that is giving the ECM bad temp data (Called bias error), which you just solved by moving the MAT to a cold spot and lying to the ECM about the true intake manifold air temp.
In other words the MAT or the MAT wiring is telling the ECM the temp is 250 (estimate) when in fact it is 150 F (estimate). You fixed the bad MAT error bias for now by moving the MAT location (in part) I think. yes I know it is a different MAT.
Mine was a high idle problem caused by a bad MAT, it was doing the opposite of yours, telling the ECM it was cold when it was hot I guess. The way to test one I think is to use ice/water to test for 0 F, and boiling water to test for 212 F (at sea level) with an ohm meter.
The truck is running cooler but that may just be from the weather"
In that case I think you found the cause of the low idle, a bad MAT or a problem with the intake manifold temperature where the MAT mounts (an exhaust leak blowing on it there? But that is a real stretch though).
The MAT needs to react fast to air flow rate changes, and any dirt or oil or soil on it will make it slow to respond. But at idle the air flow rate should be pretty steady, so ..... That leaves an MAT that is giving the ECM bad temp data (Called bias error), which you just solved by moving the MAT to a cold spot and lying to the ECM about the true intake manifold air temp.
In other words the MAT or the MAT wiring is telling the ECM the temp is 250 (estimate) when in fact it is 150 F (estimate). You fixed the bad MAT error bias for now by moving the MAT location (in part) I think. yes I know it is a different MAT.
Mine was a high idle problem caused by a bad MAT, it was doing the opposite of yours, telling the ECM it was cold when it was hot I guess. The way to test one I think is to use ice/water to test for 0 F, and boiling water to test for 212 F (at sea level) with an ohm meter.
both MAT's are clean and tested right.
Amazingly no exhaust leaks. the weld i put on the manifold actually held.
the idle is the same with the MAT in both locations with either MAT. it was just a mod i saw and thought I'd try. Its a nice improvement but we shall see.
No idea what actually fixed it. maybe the ECU needs to see the resistance from the EGR solenoid.
Amazingly no exhaust leaks. the weld i put on the manifold actually held.
the idle is the same with the MAT in both locations with either MAT. it was just a mod i saw and thought I'd try. Its a nice improvement but we shall see.
No idea what actually fixed it. maybe the ECU needs to see the resistance from the EGR solenoid.
cruiser54
NAXJA Forum User
- Location
- Prescott, Az
ECU could care less about the EGR solenoid.
thats what i thought but its mostly fixed now so i'll leave it alone for a while and see what happens
just a small update.
mpgs are around 10. but thats city driving in Ft4wd in winter with about 300# of crap in the back.
also the 33x12.50 MTR/Ks and stock gears probably arent helping.
I'd say my mpgs are much better. before in these conditions i was getting about 7...
mpgs are around 10. but thats city driving in Ft4wd in winter with about 300# of crap in the back.
also the 33x12.50 MTR/Ks and stock gears probably arent helping.
I'd say my mpgs are much better. before in these conditions i was getting about 7...
finally got the EGR valve working. the vacuum disc between the solenoid and EGR valve was faulty. and since the EGR vale on my other truck is faulty I switched the vacuum orifice? disc to my truck. now at OT when you blip the throttle the EGR moves..
they dont mention it in the test but that EGR only moves maybe 1/16"
will report back with MPGs
they dont mention it in the test but that EGR only moves maybe 1/16"
will report back with MPGs
