Outer Limits 4x4 Board

Driving to work this morning and the Feroza has decided to start idling at around 1500RPM, plus it is surging by about 400RPM twice per second around this RPM!

Any ideas before I brave the rain and try to fix it...... I did a quick check of the throttle body and it appears to be closing properly and there was nothing obviously amiss.

G'Day David,

It sounds like a vacuum line is leaking. Spray some carb cleaner or starting fluid around all vacuum lines and see if you notice a big increase in rpm. Could be timeing also. If the vacuum lines are OK then check your timing. Mine was severely retarded after having some work done and was going from 1000 to 1500 back down to 900 and up to 1200 etc. No steady idle out of the thing. I checked for months looking at sensors and vacuum lines. I finally got the service manual out and started troubleshooting. I bought a timing light and found that the timing mark was about two inches to the left of the notch. It is a wonder that the truck even ran. I adjusted the distributor and brought the timing to near specs and it is running GREAT! Bastards probably wanted me to bring it back to the shop for another wallet reaming. Also I reset the computer. I was reading the 4Runner manual and it stated that the computer can take up to 40 start/running sessions to program your trucks parameters back in. I don't know whether this is true for Daihatsu's or not...

Maybe some help.

Take care,
Kent

Thanks for the suggestions. I went back out yesterday and it was running fine- I could simulate the surging by slightly depressing the accelerator while it was warming up (TPS switch just closing I assume?) I also didn't have any problems on the way home.

This morning exactly the same thing happened! Tried turning all the electrical gear off (headlights etc) with no change. Tried disconnecting and blocking all the tubing air feeds into the throttle body with little change too. So I turned it off and immediately re started it- the idle was up around 1500rpm but the surging stopped!?!

I'm beginning to suspect the air bypass valve in the throttle body is sticking- or something like that and not closing as the coolant temp rises. Will check timing and a few other things tonight.

OK. It's started to be a more permanent fault now.

It's the cold start air bypass valve in the throttle body not shutting off. Has anyone had this fault and found a fix? I'm pretty sure the manual says to replace the throttle body......

I wonder if this http://www.outerlimits4x4.com/PHP_Modul ... php?t=3185 has got anything to do with it playing up ??
























If it ain't broke......don't fix it !!

Nice try Besty! Stop giving away my power secrets.

What I did has got nothing to do with the cold start air bypass! The cold air bypass is a small port infront of the throttle butterfly, coolant is fed into the TB and causes a valve to open when the coolant is cold, letting air through this port and past the throttle butterfly. Once the coolant gets hot the valve is supposed to shut and reduce the idle speed- mine isn't. I modified the throttle butterfly which has got nothing to do with this current problem- it seals perfectly - but thanks for your concern!

I had this sort of problem and fixed it last week: At the back of the engine beneath the distributor is the water jacket coolant temperature sensor. un plug it and clean the connections! I used mag wheel cleaner (my dad's suggestion) and now it idles at 900 (which beats 2000rpm!)

redwards wrote:I had this sort of problem and fixed it last week: At the back of the engine beneath the distributor is the water jacket coolant temperature sensor. un plug it and clean the connections! I used mag wheel cleaner (my dad's suggestion) and now it idles at 900 (which beats 2000rpm!)

What ever you do - DON'T BREAK THE F***ER......

$100 for a replacement, and they have to be imported form Japan. Like the distibutor caps pre-94 i believe.

Heath28 wrote:
....$100 for a replacement, and they have to be imported form Japan. Like the distibutor caps pre-94 i believe.

Aren't all Daihatsu spares imported from Japan???!!! Or are you talking non genuine parts? I got a genuine dizzy cap for my '92 in two days- had to come from the warehouse in Melbourne as they don't keep any spares in stock for Ferozas here.

I also can't see how the idle can sit at 2000RPM just from the coolant sensor causing problems- bearing in mind the ECU only controls the mixtures, not the timing. There would surely have to be a manifold leak involved too- or the idle air bypass sticking open?

Make sure you wash all the mag wheel cleaner off or else you might find your wiring getting eaten away! Most mag wheel cleaners are alkaline AFAIK.

spares? from japen? not from what i'm aware of.... i managed to get the pass. side window for hard top and driver side window from tiwain.... took about 3 days to get here and i only paid $60 in shipping so... ;shrugs; i dunno where they come from. lol

Fluctuating Idle Article by Ross McLean

http://www.warfs.org/content/view/45/63/

OMG did someone say thread revival??

I had this a while back. Airbypass valve was playing up (jammed open) Test by putting a thumb over the intake to see if the surging goes away. I got a whole lot of RP7 down in there and somehow got it moving again by prying at it with a bamboo skewer (Special Tool #5436-99a)

I used a screwdriver- easier to find than bamboo!

Ive just pulled off my thottle body to fix this problem, it seems i cant push the valve all the way closed, it should go all the way in right? ive put tonnes of WD40 in there (both sides) and fiddled with it... will it eventually "click" into place? or is it worth grabbing a new throttle body? Ill keep at it n check back for a reply soon!

Doesn't sound like the TPS switch as described in my WARFS article as in my experience its casues around 500 RPM change - not the massive change you are experiencing.

Don't forget that the Feroza HD engine is almost identical to the Applause engine and so second hand sensors are easy to get...

The throttle body is mechanically identical but may have a later ( and better designed ) TPS but from memory the plugs different.

Repco can supply Champion dissy caps and rotors - Applause caps are slightly different in that the leads come straight out rather than @ 90 degrees

The thermostatic bypass can stick and can't be pulled apart - but others have washed them out sucessfully. A massive rapid surge doesn't sound like the thermo idle system however - more likely a vacuum line as others have suggested.

The feroza ECU is a dumb as.... its about smart enough to squirt fuel but no much more so don't look for "learning capability"

Im talking about the valve inside the throttle body just before the butterfly... i took off the TPS aswell and has a look all seems ok, although since putting the whole thing back together this seems to have made things worse... even with my finger blocking the valve i am getting a high idle with occasional 300rpm pulse every few seconds, whereas it would run fine before with my finger blocking the hole... im worried i might have stuffed something up.

ok fixed that last thing (gotten worse since puttin back together) a vacuum wasnt connected so disregard that...
I am still having the problem with the valve not closing, i can not physically push it closed with a screwdriver which makes me think it is jammed...
I just need to know how hard I am sposed to push it in, without breaking it, and anything else i can do to get it moving.

Cheers

Rob

It's ages since mine was playing up (almost three years actually!) - all I can remember is the screwdriver could sort of move the valve and with WD-40 it started working again. Carby cleaner could be worth a try, followed by more WD-40?

Have you checked the coolant flow through the pipes in the base of the TB? Remember the valve will stay open until the coolant heats it up inside by flowing through the pipes. Make sure the engine is up to operating temp before checking if the valve is closed.

Yeah mate checked coolant flow its no problem, temp is hot.
I put about a half can of WD40 in it and drained it out
I was just wondering if you should be able to move the valve freely.
Ill chuck it back on in the morning and have a look if its working.
Either way is good because ive got a throttle body to pick up on saturday for free

From memory the valve was very much like a thermostat in the way it operated. I remember I could feel a spring type pressure pushing against the valve when probing with the screwdriver.

Hey david,

Could you possibly take some pictures of the engine, labeling the throttle body and the air hoses everyone is referring to?

Sam

It's a bit hard now as I don't own the Feroza- it got sold a couple of months back!

I managed to create just such a surge when adding an AC idle up valve. Using it to increase the idle when running the winch.

If the adjustment is too far open it surges. The valve is vacuum operated, when it opens ( too much ) the vacuum falls and it shuts, vacuum then rises then its opens etc and so on

It picks it vacuum up from a port on the side of its own connection to the plenum and therefore is very sensitive to the changes in vacuum it causes.

I'm not saying this is the cause of other peoples problems, and if you car doesn't have AC then its definitely not it - but it does cause what sounds like the same symptoms.

I think there's also a fault in the ECU programming as I could simulate it by holding the accelerator slightly open on mine. I think a lot of these high idle faults cause the engine to hit this "zone" and then it starts the whole erratic/ pulsing idle off.