hey, same engine as all 04-07 2.4l+ accord 4cyls...

this vehicle stalls only when hot.it's intermittently when you are sitting in stop and go traffic(0-1mph) and you lightly apply the throttle(no more than .70v if you know what that means). the engine will sometimes stumble and recover and other times just flat out stall(as quickly as if you were to shut the engine off normally).
btw - .70v is equal to this: your foot resting on the accelerator pedal and pressing it down a millimeter or two.
fuel is ok, normal 89 octane, no water or alcohol.
iacv is new.
no misfires or dtcs.
no accidents.
no visual wiring damage.

i have 5 high speed snapshots of the data list when it's happening and nothing appears out of the ordinary. techline is stumped so far, will get back to me on monday.

any ideas? i want to come to work with a vengence!

 

On the freeze frames you have what is the map reading doing just as you come off idle and start to open the throttle plate?
Like maybe tight intake valves are dropping the vacum?
Techline says noisy valves are happy valves. LOL
At .7 TPS the timing should start to change also.

 

yeah, sparking timing starts to advance toward 15-20degrees.
map = .88v at idle no load, 1.05v at idle loaded(normal) and approaches 1.25-1.50v depending on the throttle opening. the valves are normally quiet as well. my head is aching over this thing.. 38,000 miles on it.

 

If the scanning software isn't picking up anything strange, what can't your system monitor?

Can the fuel system be monitored with your scanner? Like a drop in fuel pressure (sticking FPR) or injectors not opening when you start off. Is it possible to feed a fuel pressure gauge through the hood, tape it to the windshield and watch it while you are trying to get it to stall. Maybe try the same thing with a timing light if possible?

 

this is the honda hds scantool. fuel pressure isn't monitered. however, fuel pressure is normal when tested with a gauge. it had a fuel system cleaning performed(induction, liquid drip and gas additive) and still no change. injector pulse width does not do anything out of the ordinary, nor does the lambda sensor or short term fuel trip drop off. [sm=sigh.gif]????

 

I was thinking that the tests will turn up ok while the car is running normally, but you might want to try to physically monitor spark and fuel when it stalls.

The pulse width indicates that the ecu is grounding the injector for a period of time, but you might not know if the fuel is getting to the cylinder. It is worth a shot if all the sensors/ecu are working properly.

 

my thoughts exactly. fuel pressure does not drop off during the stall. nor does it leak down after the stall.
spark is there until the stall, so it's difficult to say what happens there.
so i took 5 high speed snap shots that view the data on a very high resolution. it's set up like this:

upon the engine rpm falling below 450rpm the scantool starts to record what is happening 30 seconds before the rpm falling and 30 seconds after the rpm falling. it lets you view the data on .2 sec increments.

during the stall the injector pulse does not drop off, short or anything. the computer actually increases injector duration 2-3 fold to try and keep the engine running, from say 3.5ms to 8ms or as much as 11.76ms! so it leans out badly, yet stfm is 1.0 and ltfm is 1.0. so i believe the issue is either spark or the intake cam adjustment solenoid. if the cam solenoid is sticking or something odd it can mess with the intake cam valve timing. this isn't vtec or spark timing, actual cam shaft rotation alteration..hehe...

it's so tough to try and figure this out since the data list is showing everything is ok, but the engine speed drops... techline has a few confirmed fixes from new pcms...but it's just guess work. it really sucks. throw a thousand dollar pcm at it(warranty of course) and see what happens..pffff....i was hoping someone had run into a similar condition as this..

 

update: turns out the VTC system is malfunctioning. VTC is variable timing control. its a separate system from Vtec. it controls the actual timing of the camshaft itself, thus affecting valve timing in relation to the crank.

the VTC CMP command(computer target)and CMP control(actual actuator) should be very close if not exactly the same. on this car when it would stall the CMP command would be .5 degrees to 3.5degrees and the CMP control would be over 30 degrees!!!!!!!!

i ordered a VTC solenoid to start with, since the actuator is part of the camshaft(need to remove the timing CHAIN to replace it!!!! lets hope the solenoid is just sticking and i don't need to tear apart the engine..

 

i replaced the vtc solenoid and now the vtc command and vtc control match up again! no more stalling.

 

Joe again figured out his car problems again...
Way to go Techie