High idle then suddenly dies

odds1 · Post by **odds1** » September 24th, 2006, 3:05 pm

Hello

I did the KLDE swap about a month or two ago and it has been running fine until today.

Here we go:
Suddenly when i pressed the gas pedal it kinda boggs or hesitates for a second or two before it starts accelerating. When I stopped at a red light the rpms went up to about 3000 and stayed there.
When the light turned green It drove for about 10 meters and the car just died. I had to push it out of the busiest intersection in the city in rush hour. It woundn't start for about 10 minutes after several attempts.
It finally started when I had the gas pedal all the way in. Probably flooded in gas. I got black smoke when it started. I hade done the HEI mod but not external coil. I have adjusted TPS, timing and idle before this happened.
And my plugs, wires rotor and cap are pretty new. about a month.

Can anyone please help me out a little here?

PATDIESEL · Post by **PATDIESEL** » September 24th, 2006, 3:29 pm

Sounds like a vaccum leak or the sir sensor has gone out. Check for vaccum leaks and post back. Probably a decent size leak since it will only idle very high and the car will not start without the gas all the way down.
Check for spark at the plug too.

odds1 · Post by **odds1** » September 25th, 2006, 12:12 pm

Hi.

I checked for leaks and i did not find any. Then I checked once more with the same results.
What and where is the sir sensor? how do I check if it is bad?

I might be wrong but I think the thing with the idle almost just happens when I bring the car to a stop. At a light or parking.
But the engine jerking happend when driving.

all help appriciated

PATDIESEL · Post by **PATDIESEL** » September 25th, 2006, 11:44 pm

Sorry, typo. I meant Air sensor, some call it a VAF or MAF. They are not hard to check, but you will need to read about it in the online shop manual. I haven't had to do it yet, but read how to once, it sounded pretty easy. A simple ohm test if I remember correctly.
Do you have a auto or manual trans?
If it only happens when you put the car in neutral on a manual trans then check the neutral switch on the tranny. The wires run really close to the axle and if broken the car will not catch the idle when you go into neutral.
If auto trans it is a common problem, try switching into neutral when stopping instead of staying in drive and see what happens.

sampsonmx3sv · Post by **sampsonmx3sv** » September 26th, 2006, 8:21 pm

Have you taken out your plugs to inspect them. Also my car used to do that when the screw at the top (where the acc cable attaches), sorry long day.I used to have to readjust it. just a couple of thoughts...

odds1 · Post by **odds1** » September 27th, 2006, 2:37 am

I have a manual. Checked the air sensor and it was within spec.
I have let tha car idle in my driveway for some time. Normally it idles at about 600-800 rpms. but sometimes it jumps to maybe 1200.
But then sometimes I suddenly hear loud sucking sound from the air filter and the rpms jumps to about 3000 and stays for about a couple of minutes. If I push the gas pedal or sut the engine off when at 3000 rpm, it willl not start again for about 20 - 30 minutes and will smoke very black when started..
If I let it run it will very suddenly fall down to 1200 og 800 around.

I hade tried set the idle speed and timing again, but it didn't get any better. I wil check the plugs today.

It suddenly hit that it may be because I still run the K8 ecu but the KLDE air sensor.
What are your thoughts guys?
And thanks for all help..

Odds

sampsonmx3sv · Post by **sampsonmx3sv** » September 27th, 2006, 8:44 pm

I ran a klze with a k8 ecu and a 2.5 air sensor. I havent read about that being a common prob though.

hgallegos915 · Post by **hgallegos915** » September 27th, 2006, 9:05 pm

I had to adjust the top screws (throttle fly) and the idle screw alos..seems that theres 2 diff adjustments, when i use k8 ecu it dies like you say and i have to readjust whenever i swittch ecus.. go figure o.0 weird huh Its driving fine now.

odds1 · Post by **odds1** » October 2nd, 2006, 3:31 am

This i starting to get really irritating.

I took the black rubber thing from the VAF to the TB off to check that the TB closed properly and it did. Then started the car and let it idle.
When the engine reved itself to 3000 rpm. the TB didn't open at all.
Is it the IAC than lets air in that can be the problem? Can I try to run the car with the IAC unplugged?

I have a KLDE IAC can I use the IAC from my K8?

PATDIESEL · Post by **PATDIESEL** » October 4th, 2006, 12:04 am

Could be a bad IAC. I don't think that the IAC are compatable from K8 to DE to ZE. Check the part numbers and such and try it if you have one. Easier to try yours and know it doesn't work than spend the money on a new or used one and find out later you could have used the K8.

foca · Post by **foca** » October 4th, 2006, 8:39 am

sounds like a stuck idle air control valave.

odds1 · Post by **odds1** » October 9th, 2006, 5:02 am

I disconnected the IAC and the car runs great. Is it Ok to run without it?
Mazda wants almost 2000$ for a new one. And I am not paying that.

foca · Post by **foca** » October 9th, 2006, 12:47 pm

hmmm, you can run without it, but not well. The IAC controls the idle as environment varies (pressure, outside temp, engine temp, A/C on, etc.). If you dump the IAC, you will not be able to achieve a good idle. try to source a good used part somewhere.

o4_boyracer_no1_o5 · October 9th, 2006, 6:07 pm

i know it might have been awhile ago when you had this problem with the revs i had the same problem with my k8 engine i found out one of my ht leads were gubbed lol when its firin but not properly it seams torevs the life out itsself then go to normal check them it was still running ok but it was through the roof also it couldnt be the airflow meter because it would constantly rev up and down it could only be the vacum idle air control valve which is on the throttle bottle hope this helps

max kl · Post by **max kl** » October 10th, 2006, 2:35 am

want a good iac?