Misfire and stall on idle (1 Viewer)

[Brayden3223]

Hey guys I’ve got a 1997 1fz-fe (Australia) and I have a bad misfire on idle, once the car warms up from a cold start it will begin to happen and will drop low enough that it stalls, taking off from the lights, it feels like it has no power until around the 2500rpm mark and then just takes off (like it has powerband). It also has extremely poor fuel consumption. The car is dual fuel so it runs on petrol and gas and Has no O2 sensors or cats from factory

any ideas? Cheers

 

[bubfuji]

Check your air intake tube for cracks/tears. When you accelerate, the motor can shift slightly, if the intake tube is cracked it will open allowing un-metered air into the engine. When the engine settles back the cracks will close again. A weak/bad motor mount allows the engine to shift more than designed. One of my motor mounts separated completely. So Every time I reversed my rig the engine would move enough to pull apart my intake hose and loose power. The engine would magically run great again driving forward.

 

[LINUS]

+1 to the intake

A/F ratio at idle magnifies when something is off.

-You mention dual-fuel, is this propane & gas or did you do an E85/gas thing?
-Does either fuel magnify the idle issue, or ballpark the same?

Also, just curious - is ‘97 over there still rotor & dist cap, or did they already go distributorless for ‘97 outside the USDM?

 

[mudgudgeon]

+1 to the intake.
A/F ratio at idle magnifies when something is off.

-You mention dual-fuel, is this propane & gas or did you do an E85/gas thing?
-Does either fuel magnify the idle issue, or ballpark the same?

Also, just curious - is ‘97 over there still rotor & dist cap, or did they already go distributorless for ‘97 outside the USDM?

Dual fuel in Australia means petrol / and aftermarket installed LPG (liquefied petroleum gas) systems.

LPG was previously heavily subsidised/ tax exempted by the federal government. It was about 20-25% the cost of petrol for a long time. It's was dubiously cheaper to spend 7-10k on a conversion (tanks, evaporator, 'gas carburettor', and switching systems etc ). Pay off was in 7-10 years of higher than average use/ mileage.

Systems are problematic many ways. Lots of engine failures. Certified gas mechanic required to work on them. Annual inspection and certification of the system,10 year removal, pressure test, cmre-certification, reinstall of tanks.

 

[Brayden3223]

+1 to the intake

A/F ratio at idle magnifies when something is off.

-You mention dual-fuel, is this propane & gas or did you do an E85/gas thing?
-Does either fuel magnify the idle issue, or ballpark the same?

Also, just curious - is ‘97 over there still rotor & dist cap, or did they already go distributorless for ‘97 outside the USDM?

Mudgudgeon did cover the petrol/gas part just then, the engine has a Dizzy with Electronic Fuel Injection.
There’s no vacuum leaks of any sort, ive checked over the whole engine and sprayed down any possible components with throttle body cleaner. Gas it runs fine on which makes me think that it isn’t a sparking issue, I’m wondering if it could be due to a bad fuel pump that it’s sluggish and gets poor economy in the low rpm range or whether it’s a injector. I’ve even pondered on whether it’s from a tune from the previous owner if he tried advancing the timing and messed it up

 

[alia176]

At idle, the vaccum is very high and amplifies issues that mimics an "open" system, as mentioned already. If the intake air tube is in good shape, check for vac leaks, especially, those hard to reach hoses under the intake manifold. Remember, a connected hose may still have split ends that aren't as tight on the nipples.

Secondly, check the IAC (idle air control) valve per FSM. It does a lot of work keeping the engine at a smooth idle.

I realize the PO posted this thread a month ago but might help others! @Brayden3223 what was the resolution on this issue? Don't keep us hanging man

 

[Brayden3223]

At idle, the vaccum is very high and amplifies issues that mimics an "open" system, as mentioned already. If the intake air tube is in good shape, check for vac leaks, especially, those hard to reach hoses under the intake manifold. Remember, a connected hose may still have split ends that aren't as tight on the nipples.

Secondly, check the IAC (idle air control) valve per FSM. It does a lot of work keeping the engine at a smooth idle.

I realize the PO posted this thread a month ago but might help others! @Brayden3223 what was the resolution on this issue? Don't keep us hanging man

I’m still searching for it! This is among a few small problems I’m currently facing! But there isn’t any vacuum leaks at all