Searching issue

[Siret]

I have an issue of searching with my car i'm hoping someone could shed some light on.

It's a vr4 engine, microtech computer, 044 fuel pump, 560cc evo8 injectors and i'm using the BPR7ES plugs with magnecor leads and coils/transistor were new 4 months ago.

Now it's only an intermittent problem but sometimes the idle drops to about 600rpm, then back up to 1100...over and over again. Then it'll fix itself and idle fine. Then it won't.

The biggest drama is it sometimes happens when i'm cruising under 2000rpm. The engine hesitates, misfires and generally sounds like a rotary. But up top the engine is absolutely fine, no dramas.

Also the engine will be idling fine then when the thermo fan kicks in it'll start searching. Pain in the arse when i'm stuck in traffic because it's determined to stall. Thermo fans turn off and idle resumes like normal.

I've got a few ideas on what it could be just wanted to hear what you guys thought.

1. Could it be the plugs. I've read that colder plugs can cause misfire in low rpm. I am just worried about high rpm on hotter plugs as the car was tuned with the 7's....not sure if it's an issue. The idle usually improves after i've cleared the engines throat so could fouling be the problem?

2. I've also read that the stock fpr has trouble returning fuel to the tank with an aftermarket pump which can cause running rich issues. Searching is usually the engine leaning out so dunno about this. I'm trying to avoid going to the tuner but i guess knowing what fuel pressure i'm running would help.

3. My cas is seeping oil from the internal seal, not the o-ring. Could oil on the sensor cause these issues?

4. The thermo fan i'm using is old. Could this be drawing too much amperage and weakening the spark...or pump voltage?

Sorry for the essay but the problem shits me. Any help is much appreciated.

 

[CLuTZ]

You cruise at 2000rpm?? :wacko:

Do you have aftermarket cams?

 

[bazeng]

You well probably need to check your main items:
1. Base timing
2. Idle speed screw adjustment with timing disabled
3. Voltage drop when fan kicks on, it should be caught by your ecu with battery voltage compensation / dead time values.
4. Earth system check on engine / battery / ecu system
5. Post t/b air leaks. Do a pressure test on your intake system.

Depending how your microtech has been wired in, you most likely have no idle control.

Which means no aircon / power steering switches bump up idle either...

 

[4piknup]

I was going to say idle speed control issues, but I'm not familiar with your ecu. Also maybe it has voltage compensation that needs tweaking

 

[Entaran]

Could also be an old/sticky throttlebody and/or a stuffed wax pellet in your fiav. My car started doing similar crap to this when I blocked the FIAV and then stopped when I unblocked it which is relatively the opposite of what should happen. Go figure

 

[Siret]

You cruise at 2000rpm?? :wacko:

At 60km/h yes. Going past speed cameras can be a pain. On the highway i'm around the 3000rpm at 100-110km/h...but the car is fine at this speed.

Could also be an old/sticky throttlebody and/or a stuffed wax pellet in your fiav. My car started doing similar crap to this when I blocked the FIAV and then stopped when I unblocked it which is relatively the opposite of what should happen. Go figure

I've blocked my fiav. What is this wax pellet you speak of? Never heard of it

You well probably need to check your main items:
1. Base timing
2. Idle speed screw adjustment with timing disabled
3. Voltage drop when fan kicks on, it should be caught by your ecu with battery voltage compensation / dead time values.
4. Earth system check on engine / battery / ecu system
5. Post t/b air leaks. Do a pressure test on your intake system.

Depending how your microtech has been wired in, you most likely have no idle control.

Which means no aircon / power steering switches bump up idle either...

My car has no idle control. The tuner apparently enriched for start up...not quite sure what that means. When cold timing is around 15degbtdc and gets to 5 when warm.
My car has no aircon and it happens when i'm driving in a straight line...so unlikely to be power steering. When the idle is searching the afr's are all over the place....but i've been told the microtech handset gives values that should be taken with a grain of salt.

I'm thinking i'll have to do an earth check and intake pressure check and find out more about this wax pellet thing with the fiav. Cheers for the replies.

 

[Entaran]

Out of interest, is your narrowband sensor playing up? Have you checked the wiring?

 

[Siret]

The wiring is all good. I haven't put the multimeter on it because i never get the problem at home. It always happens when i'm in traffic. It's a good point though, worth looking into.

Just wondering what the wax pellet in the fiav is. I've blocked the fiav with a meek block off plate using rtv blue to seal it. Would the wax pellet even apply after this?

 

[4piknup]

the wax pellet thing...
works like a thermostat, sort of. the faiv is open when cold allowing extra air around the throttle blade giving a faster idle. as coolant warms up the wax pellet melts and the port closes.

like when you take the choke out of a carby car, dont expect both a nice cold idle and a nice warm idle if you have blocked the faiv. its tuned for one or the other. especially if you have no idle control as well

 

[turbovr4]

I would say it is your FIAV valve, I have a similer problem with my haltech E6X on a vr4 motor, when i tuned the haltech i found the idle control valve had trouble with certain conditions,
best way i could tell it was the fiav valve, is that my car would struggle to idle if i drove the car till warm then stopped for about 10mins, then start it. the car would struggle to idle and you could hear the idle speed contoller struggling. after 5mins of driving it would idle not to bad again. that is the setup in my MGB, and my factory eterna had the same problem with a factory computer till i unblocked the water lines to the fiav .

 

[4piknup]

I would be fixing the cas as well.
A guy in the vr4 section that has just done this. It has the part numbers and how to do it

 

[Siret]

Yep i just got a secondhand cas in the mail that i'm going to rebuild.

I don't think it would be my fiav valve as i removed it from the tb and used a block off plate.
Is this the fiav valve?

Maybe my block off plate is leaking. I'll replace cas and check ground wires and see what happens then.