very strange problem @ idle & no power.

[nitromethane]

i have a 98 ek9 with the strangest problem at idle & no power through out the rpms.
possible two separate problems or they're are linked somehow.

when the engine is started cold it idles fine for a couple minutes even with the ac on. after the couple mins 3-4 mins if you turn on the ac the idle drops really low, when you turn it off the idle raises up then settles back normally. if i take the car for a spin and run it hard, @ idle the engine fluctuates anywhere between 800 to 2000rpm, sometimes it holds @ 2000 rpms for a while then returns to normal. i have swapped every sensor on the engine, iacv,etc. valve clearances checked over. engine timing checked over. vacum is good, no leaks. we have swapped ecu's with 1 other known owrking b18c, the b16b ecu worked fine on the b18c but the b18c ecu didnt work very well on the b16b even though it did make the idle with the ac normal.

also the engine has absolutely no power and is burning very lean as if the plugs are still brand new in color.
voltage 13.8 is good at idle and while running.

also, little things like: playing with the throttle (off throttle 1-5%) i can make the problem show itself.

what are y'all thoughts?

 

[Joshm88]

Sounds like a similar problem to what I experienced after swapping in my stroked b18c. I know you said you've checked iacv etc but I'll list a few things to check:

Iacv
Tps voltage
Map sensor
Vacuum leaks
Wiring loom, may be shorting on the back of the block?
Thermostat
Air locks in the coolant
ECU codes
Swap with another ECU known to be working
Cracks on the intake manifold
Check TB isnt bolted too over tightly to the IM
CTS sensor
Check CTS resistance decreases as engine warms up using multimeter
Have you checked the AFR? Any particular reason it might be running lean, have you upgraded your TB size, what is the spec of the engine? Is it running on oem ECU?
How did you check the IACV, did you try blocking the coolant ports on the front of the TB and record the results?
Did you clean the IACV?
Possibly worth checking the distributor as well, especially if it's a B18C?

Are there any other symptoms? Hunting sounds like vacuum leak or IACV, could also be FITV if you have one on your motor?

A lot of things probably you have already done, and some you may think are unrelated, however when tracking down my issue I more or less exhausted every possible idea!

 

[nitromethane]

Iacv - swapped at least 2 known working
Tps voltage - readings are good also swapped with other known working unit
Map sensor - good, also swapped
Vacuum leaks - vacuum reading is good
Wiring loom, may be shorting on the back of the block? havent checked yet
Thermostat
Air locks in the coolant -no air locks
ECU codes - no ecu codes
Swap with another ECU known to be working -swapped, idle problem got better but overall performance still suffering
Cracks on the intake manifold - none
Check TB isnt bolted too over tightly to the IM - no
CTS sensor - good
Check CTS resistance decreases as engine warms up using multimeter
Have you checked the AFR? Any particular reason it might be running lean, have you upgraded your TB size, what is the spec of the engine? Is it running on oem ECU? no upgrades, stock engine.
How didk the IACV, did you try blocking the coolant ports on the front of the TB and record the results? didnt do this
Did you clean the IACV? yes
Possibly worth checking the distributor as well, especially if it's a B18C? swapped the entire dizzy with a known working b18c external coil

Are there any other symptoms? Hunting sounds like vacuum leak or IACV, could also be FITV if you have one on your motor?

the motor isnt hunting, the idles just suddenly raises on its on and then drops back down to normal sporadically.
i will mention also the compression is 175.

 

[nitromethane]

anyone have any ideas? at this point i want to test and swap the only sensor i havent yet, thats the crk sensor!!
other than that......pull the engine to check through the harness and rebuild the bitch while its out....

 

[Gorbash12346]

have you done a compression check?

 

[Boyle]

You may have an air lock in your cooling system or not enough coolant.

You prob already done this but thought to mention

 

[Vtec6000]

02 sensor.....Plug it out and then see how the car runs.

 

[nitromethane]

i tried pulling the 02 sensor and running it, same **** !! lol
im sure the cooling system has no air but i will double check.....but how does thatexplain the dropping of the idle as i turn on the AC on OR if i play with the throttle 0-1% kinda ting......AND how does that explain the raising of the idle on its own.

if i take it for a run around the block and stop the idle shoots up to 2000rpm out of no where for random amts of time and patterns lol.....its whack !!

the compression is down to 175psi.....its low, i told my cousin he should do a rebuild at this point plus im sure that engine has over 100,000k on it with no rebuild.
we used the came compression gauge on my bros b18R and he got 200+......

 

[SiW]

175psi on what? All across the board or on one cylinder? The aim of a compression test is really to evaluate the compression on all 4 cylinders, so just saying 175psi doesn't give much information. It is a little low, but then again that's subjective, what are the results for each cylinder?

 

[Gorbash12346]

175psi on what? All across the board or on one cylinder? The aim of a compression test is really to evaluate the compression on all 4 cylinders, so just saying 175psi doesn't give much information. It is a little low, but then again that's subjective, what are the results for each cylinder?

175psi is very low and although he hasn't listed wether there is differences between each cylinder at 175psi i'd be taking the head off it and seeing what the damage is.

 

[SiW]

175psi is very low and although he hasn't listed wether there is differences between each cylinder at 175psi i'd be taking the head off it and seeing what the damage is.

I'd agree that 175psi is low, but I wouldn't say very low and it wouldn't be the only factor in me removing a head. The relationship between cylinders tells you a lot more than knowing the average

Did you do the test WOT? I'd get the compression done wet, you can get a feel for the state of your rings then, a little blow by could explain the numbers. If the numbers don't increase then your not loosing compression through worn rings, which could be down to valves/timing etc. Check the timing again and get a leakdown if that is the case, will tell you where your looking at issues related to compression

 

[nitromethane]

ok 175psi is on all 4cyls......this is a norm compression test with throttle opened, we also did a wet test and got 190psi on all 4.....

i told my cousin it is time for a rebuild anyway because of the amt of KMS on the clock...
but this problem is beatin me... cause we changed everything on the engine besides the harness and the crnk sensor.

wen we swapped the ecu (used a b18c GSR), the idle bog/raise stopped but the car still lacked power badly still......
its like 1000RPM vrooooooooooooooooooooooom 6000RPM VTEC BARRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR and we not going anywhere quick lol....its quite funny lol....
but anyway back to d topic....