Need to rev engine for it to run right.. strange (1 Viewer)

[Kkxrw]

Hi i have a 1994 lc and i have a strange problem with it.

Problem
when i start the truck when it is cold it idles smooth. if i try to drive it right away the truck engine runs really rough.

I noticed if I start the truck when it is cold, then wait about 10 seconds (for oil pressure to build up), then rev the engine to 4k or 5k rpms 2 or 3 times, then drive the truck the engine runs smooth.


Over the last several months i have replaced the following:
-cap wires plugs and rotor
-fuel filter
- fuel pressure regulator
-iac
- throttle position sensor
- cleaned throttle body
- replaced all vacuum lines
- battery
- fuel pump
- vaf ( i have 2 and it runs the same with both)
- air filter
- fuel relay
- relay in drivers side kick panel
- new coil


Any help is appreciated. Thank you

 

[voodu3]

Have you checked your throttle cable? They get worn and hang up. You might try lubing it to see if it improves. If it hasn’t been replaced it’s 30 years old and is probably due.

 

[Kkxrw]

Have you checked your throttle cable? They get worn and hang up. You might try lubing it to see if it improves. If it hasn’t been replaced it’s 30 years old and is probably due.

I forgot to mention the throttle cable is about 6 months old.

Thanks

 

[george_tlc]

So, did this problem start before all the 'repairs' or during or after?

A bit of a timeline/history of the problem versus the 'repairs' would possibly help narrow things down.

cheers,
george.

 

[mudgudgeon]

Have you checked the timing? How much static advance are you running?

 

[cruzinfj1]

Check the intake tube itself. Wonder if its cracked/split. Mine did some really weird stuff to because of this...

 

[Kkxrw]

Hi

I Bought the truck about 2 years ago and have been fixing it up. The battery died in December ( l left the door open And light was on ) and ever since it has run rough

The intake hose is in good shape

The timing is set to 3 degrees.

Its strange that it idles smooth but if i dont rev it before i drive it hesitates and runs like crap


Thanks

 

[Malleus]

I had a similar problem with my son's '94 last month. The problem was the idle air control valve. It was fine when cold, because the valve was stuck closed. We removed the throttle body, cleaned it and removed/disassembled/cleaned/reinstalled the IAC. Now it works as it should.

The testing procedure for the IAC is in the FSM. You'll need to remove the throttle body to remove the IAC. Follow the procedure exactly as written.

FWIW, the '93-'94 IAC is NLA, however, the '95-'97 IAC is a direct replacement. Used is about $100; new is ridiculously more. This same component was used on many Toyota models, so don't restrict your search to Land Cruisers, if you have to replace it.

 

[rc51kid]

Also if problems started after replacing the battery eye ball the area around the battery. Make sure you didnt pinch or break any wires or vacuum lines when you were working in that area.

 

[Kkxrw]

Also if problems started after replacing the battery eye ball the area around the battery. Make sure you didnt pinch or break any wires or vacuum lines when you were working in that area.

Thanks done but prpblem still exists

 

[Halfpint]

Check the intake tube itself. Wonder if its cracked/split. Mine did some really weird stuff to because of this...

Mine acted the same at startup until plastics got up to temp then it would not display the symptoms (I assume it expanded enough to "seal" the crack). There was a hairline crack in the intake tube - field repaired with duct tape solved the issue until it was replaced with silicone tube.

 

[Kkxrw]

Mine acted the same at startup until plastics got up to temp then it would not display the symptoms (I assume it expanded enough to "seal" the crack). There was a hairline crack in the intake tube - field repaired with duct tape solved the issue until it was replaced with silicone tube.

Thanks i checked it once and willdouble check.