1fz-fe throttle hesitation.

[Glenn-80]

Hi all

Ok so my 93 fzj80 started massively hesitating on acceleration today. Just wanted some ideas on where to go from here.

I'll be checking for codes on lunch break tomorrow, but thought I'd get some opinions while I'm on here.

Possibly MAF, TPS sensor failure. How do I check these? Possible with a multi meter? (I mostly understand them, variable resistors, check for resistance difference from open to closed? but what numbers am I actually looking for?)

I DO have a vacuum leak but it's been there for a while. Having difficulty tracking it down, tips?

For some reason I decided to throw $10 worth of e10 in the other day, tank was near low. A problem maybe? possibly water in the fuel? I've head water actually mixes with e10 as apposed to remaining separate like with regular petrol. That fuel was in there for 1-2 days, since put $40 premium in.

I had a hesitation problem like this some months ago (although this time around it's much worse), was resolved by disconnecting the o2 sensor and just dealing with the rich mixture. I reconnected it to day to have a gander only to have the car run even worse.

Thanks all, any ideas to help me sort this without going out and blowing all my piggy bank on expensive sensors that aren't actually busted.

EDIT: I should add that if I floor it, the hesitation is much less or seemingly doesn't happen at all (most of the time, varies ) AND that if i hold 1/2 - 3/4 acceleration the vehicle will 'catch up' and surge once the revs are up a bit. Excuse the poor explanations.

[howsie]

Could be starving of fuel. Check blocked injectors, o2 sensor

[Glenn-80]

Thanks for the reply. As I said o2 sensor is buggered and is disconnected, so it is out of the loop.
Just checked for codes, getting 21 and 24.

21 is o2 sensor, well I expect that code, 24 is IAT sensor. Sooooo onto more research to sort this out.

EDIT, seems as though the IAT sensor is part of the MAF/VAF sensor, this is starting to look very expensive.

Please, anyone, if you think you may know what is the issue here, other then buying a new MAF sensor... CHIME IN!!!

[4by]

Not sure if this is any help or not, but you could clean the air flow sensor first instead of buying a new one to find out its not the problem. I cleaned my air filter and air flow sensor the other day and it made a huge difference. A can of maf cleaner under $20 bucks. Only use special maf cleaner, don't use anything else.
The other option is try swap with someone you might know has a cruiser and see if it fixes the problem. Good luck.

[Glenn-80]

I may give this a try thanks, unfortunately I don't think it will work.

My car is now nearly dropping revs to ZERO if i put my foot down too fast. Also my air filter is virtually spotless.

As for swapping sensors with someone, a great idea, I just need to find someone that doesn't drive a damned diesel lol.

[4by]

Did it start happening after you put in e10 fuel?? Could have picked up some rubbish from the bottom of the fuel tank and blocked the fuel filter/ injectors?? Have you checked the fuel filter?? If it was on LPG as well it would help eliminate a few items.....

[Glenn-80]

It happened about 24-48 hours after the e10 was put in.
I dropped 1 litre of metho in just incase i got some water.

The vehicle ran on gas once upon a time, but no longer. The gas system has been removed. What was your thinking here?

As for cleaning the MAF sensor, i got the fluid, how did you go about it? just pop off the MAF sensor, spray inside it and that's all? no dis-assembly required? It's a vane type and i cannot see my it would need a lot of cleaning? so long as the flap moves freely.

EDIT: just check fuel from fuel filter, all good in there.

EDIT:: Looking at the connector for the MAF, I am missing the pin(female) 3rd from the right. This right or has it fallen out?

[UhhOhh]

I'd be chasing up any vacuum leaks you might have before looking at the sensors.
Clogged/stuck injectors from small amount of e10 is entirely possible but unlikely given the problem happened before it really depends on how it launches/when they were last serviced and dismissing the intake leak, ie. flat take off then the engine drives through it or flat/boggy all the way through acceleration? Does it surge then conk repeatedly or start with a conk and drive through it ok? When it nearly conks out is this only hard under load and can you still rev through not under load? How does it free rev?

From my understanding disconnecting an oxygen sensor will just make the ecu run in open loop, ie. disregarding the maf, water temp sensor and o2s and probably the tps sensors inputs, it just runs as if it was cold at idle even when warm and doesn't lean the mixture under low load hence the rich performance. The fact it does it both with and without the maf plugged in and/or 02 hooked up AND the car had the problem previously AND unplugging the o2 sensor fixed it somewhat suggests the hesitation problem is elsewhere. Even running in open loop all the time the car should still perform without the miss at acceleration just use lot more fuel. Lot's of intake leaks have hesitation on takeoff as a symptom as it leans the mixture out too much.

You can vacuum or pressure test the intake with smoke but I've always just carefully sprayed aerostart around the suspected areas listening for the increases in idle.


I'm not a mechanic but that's what I'd do, no point chasing a sensor problem before you've solved a vacuum problem imo.
Sorry for the long post I'm bored at work.

Good luck!

[Glenn-80]

Thanks for the reply. I just cleaned up the maf sensor and the throttle body. It improved driveability but the issue is still there, plus another code > 31 - air flow sensor.

As for how it drives, slow acceleration is fine, but once i step on it a bit more (more load) it bogs down.
-While driving if i put my foot flat to the floor it accelerates at an obviously gimped rate.
-Free revving is not too bad, a bit of splattering, nothing major.
-If I drive with about 3/4 acceleration and say for example stay in 2nd gear, once the revs are up to about 2500/3000 it will surge and take off.

the vac leak i have is crazy loud on mid-heavy acceleration. Nearly every week end I am under the bonnet spraying starter fluid around to try find it, but no success yet.

I really do not think the o2 sensor has anything to do with this new problem.

ECU says air flow sensor and intake air temp sensor is short/open circuit, apart from the obvious possibility it is that that is screwed, what else could make the ecu 'think' this is the problem (other then vac leak, still working on that)

Cheers

[4by]

The LPG idea would just eliminate the possibility of fuel system, filter or injector problem.

If you have a vac leak I'd be looking at that first. I had a vac leak around the injectors once which caused problems. I used a hose to listen to sucking sounds around the intake system.

I had a suspicion cleaning the maf would help the car run better but now reading the other posts I agree the problem could be somewhere else. Process of elimination I suppose.

My maf wiring had 5 wires in a row, mine a 95 model and could be different setup. Not sure about your pin.

Definitely curious to know what it could be. Hope you sort it out.

[Glenn-80]

Wondering if my struggle to find this vacuum leak has anything to do with revs. Just found a source saying some lines won't produce vacuum until a particular rpm is reached:

"Port R from throttle body. Doesn't generate vacuum until 3000 RPM. When it does it pulls about 5.0 in/Hg."

Mind you I have had this leak for months with no problem other then the annoying sound it produces.

A piece of hose you say? BRB cutting up garden hose.

EDIT: for the life of me i cannot find a vac leak...

as for port R of the throttle body, it isn't in use (it would seem) on my vehicle... neither is port E... only port P is in use.

[4by]

Now even more confusing if it drove well with the leak..... Keep looking for it. Pull the hand throttle and turn up the revs till its running rough and look/ listen for the leak. Keep spraying and listen for the engine revs change....

[howsie]

Another thing would be spark plugs if these are fouled it can.cause this.

[Glenn-80]

Yes the leak has been there for ages, it made f all difference and i've emptied so muchb starter fluid into the engine bay it aint funny.

As for the current problem, i am pretty sure its got nothing to do with a vac leak that has been there for months. Plugs are virtually new, leads are new, dizzy cap is new, rotor button is new.
But if it were plugs, why would the ecu be logging faults for IAT and MAF?

The car is now undriveable. Trying to source another MAF sensor just to SEE if that is really the issue.

[unsub]

If I recall you had a similar thread on 4wdaction? I was posting in there as well because I had a similar issue.

Do the 1993 cruisers have a MAP sensor? My 92' didn't originally but one was installed when I had the Sprintex supercharger fitted and I had exactly the same symptoms as you and after replacing a heap parts it ended up being the MAP sensor. As soon as it was replaced the cruiser was back to normal.

[Glenn-80]

Haha yeah I recognized your name straight away.
That issue was regarding my o2 sensor. The 93 fzj80 i own has a vane type MAF sensor, it doesn't have a MAP sensor.

Your 92 cruiser? isn't that the 3fe motor??? mines a 1fz-fe, different kettle of fish.

[unsub]

Nah mine was built in October 1992 so it has the 1fz-fe but it has an AFM instead of a MAF. It took nearly 6 months and lots of cash thrown at it only to find the problem was covered under warranty

Good luck with your 4by, I know how much of a pain it is to find a fault when all the obvious things have been tried. If you need a TPS to try out let me know, I have a spare you can have and I also have a spare ECU you can borrow if you want to try it.

cheers

unsub

[loosecanon]

Hey stranger just saw your thread, sorry Im late....

Gee mate 6mnths into your apprenticeship and you are already a pro,, your starting to talk shit that's over my head. Im really impressed. But to your problem.

First things first, are you getting any smoke of any sort? if so what colour. As for the vacuum leak this needs to be found to diagnose properly, it may not be the problem itself but it can't be doing it any good, the leak could be getting worse and starting the problem to much more noticeable.
You said the leak makes a hell of a noise, does it do this free rev or just under load? you said that you have just started getting 31 code up ( airflow) this is a pretty good indication that the vacuum leak is playing a part. The only experience I have had with these is when I had a leak on the air intake which cause a similar problem.

At the end of the day engines still need the same basic's to run Air, Fuel and spark. You have good spark, fuel is a concern but unlikely ( check your injects btw way just to rule it out) but it sounds as if air is your problem.

You know heaps more than me these days especially on these new fan-dangle electronic things. If it's possible try to by pass or use spares (from a mate) to eliminate problems. Oh by the way prozzie has a 80 he is doing some running around for me this week for my stupid unregisterable truck. Hit me up if you don't have his number he may be able to help you out with swapping.

Cheers mate

see you next week

[Glenn-80]

Hey mate, thanks for chiming in.

Smoke? no, never, a rich smell yes, but i know this is because the o2 sensor is shagged (maybe more rich now the maf sensor seems to be gone).

Vac leak, has been there for ages, do not think its worse now, BUT the car is running so terribly that i can't even diagnose/find it (not that i can find it, like i said i have tried) OH, yes it's only under load above 2500/3000rpm.

Ignition is great atm, no issue there.

Injectors were flushed about 4 months ago.

Seriously the car runs sooooooo bad now, it cannot be a little thing like 1 dodge injector/vac leak.

The problem has progressed to the point where it will not idle properly (revs race up to about 1200, nearly die, rpm bounces a little more then it will die). Put a little boot into it and it will die.

YES, the simplest way to see if it is the MAF sensor would be to borrow someone elses for 5 minutes, but nooooo everyone drives a freaking diesel.!.!.!

Oh as for my error codes, Intake air temp sendor is shooting a code, like i said a few times, not sure how this could possibly relate to fuel or vac leaks.

I may very well be wrong but i think in this case the codes mean exactly what they are meant to, the corresponding sensors are

Thanks Unsub, appreciate it. I'm going to rule out this MAF sensor first and go from there.

EDIT: would just like to say it's great for people here to shoot ideas at me, other forums (that will remain unnamed) offer very little support for diagnostics.

[howsie]

Maybe unlikely but could always be computer. This would throw your injection and firing order out of whack. Have you checked the dizzy / stupid box controller thing that tells it to fire.

[crazy eyez]

if it has codes logged it will go to defoult and they run like shit in defoult and if your o2 sensore is stuffed it will chew fuel even worse than normal ..... the air temp sensore is in the air flow meter or maf sensor and they dont like any cleaners i have found in the past as i have killed a few to learn this ...the intake pipe from the airbox to throtle body seem to get pin holes in them and are hard to find .... i would say start at airflow meter then go from there but it does sound like a airflow problem it could even be the idle steper on the throtle body they can get sticky some times...

i fixed mine by going stand alone ecu and got rid of the airflow meter now i never have a problem and if i do i can just plug in the laptop and do a diegnoses

just my sugestions