Question about 1991 Isuzu Pickup

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1990 isuzu pickup 4cl will, off and on, not idle at very low rpms and uner 15 mph. I know for sure I have a cracked ( in two places) exhaust manifold and the idel promlem seems to happening now more often than not. It was tuned up about 4 months ago and have new, clean oil ( which it burns, but not like crazy) and fluids. Is the bad manifold the reason for the idle/intake issues, or ma I looking at a whole other mess? I don't know too much about cars or fixing them, but would love to imformed before I have it repaired ( or not) Any info or advice is greatly appreciated

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It could be the problem but id also look into the tps sensor thats if it has on since its an older vehicle

Posted on Dec 05, 2012


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Posted on Jan 02, 2017

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SOURCE: Isuzu 2.8TD high erratic oil pressure problem.

Does it have a PCV valve in the system? If yes, has it been changed?

Posted on Jan 02, 2009

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SOURCE: idle issues

I had the same problem and when I change the catalytic converter the problem was solve !

Posted on Apr 26, 2009

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SOURCE: 2001 Isuzu Rodeo 3.2 V6 Oil Burning and motor tapping loudly

Do a compression test on all the cylinders and see if the rocker arms are adjusted to the right. If the compression is bad then there will be no power at all and if the Rocker arms need adjustments you could be losing some power there too.
You can try cleaning out the engine from the inside out. I have done this many times when I buy a use car. I run Marvel Mystery Oil with the engine oil for about 4 months and keep an eye on the oil level. Marvel is a thinner oil and clean out the inside by removing the carbon collected and oil sludge inside the engine.
You may end up having to replace the oil pressure sensor, it seams to always be the first to go bad and may get some oil leaks. But once the engine is cleaned up you'll have a better understanding on the condition on the engine and be surprised on how well it runs after.
Just keep an eye on the oil level and change the oil and filter to free up the engine, then use the recommended oil and add Lucas oil and or Restor to help the loose of compression.
The loud tapping tells me that your not getting the oil to the top of the engine and that may be a bad oil pump but it may also be a plugged oil pump screen and the Marvel Mystery oil will clean up the oil screen.
Good luck and hope this helps, Keep me posted on your Rodeo.

Posted on May 22, 2009

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SOURCE: where is the transmission dipstick on 1995 Isuzu redeo?

There is no transmission dipstick. You have to both check and add fluid to these vehicles from underneath the vehicle. Find the transmission fluid pan and you will find two plugs. The lower plug will drain the pan and the upper one you can add fluid or check the fluid level. You will know that the level is correct when the plug is out and fluid barely leaks out of the hole. You don't want a lot coming out because you don't want to overfill. In order to get it into the hole you have to be some sort of tube to attach to the top of the bottle. They sell these types of tubes at your auto part store and they just screw on. It is very awkward, but you can actually put the bottle high enough to get the fluid in if you put it right to the left of the pan. The first time I did this on mine it was a pain but once you figure it out you will be good to go. Let me know if you have any other questions about your vehicle. Thanks for rating my response and for using FixYa!

Posted on Sep 05, 2009

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SOURCE: 94 isuzu pickup loping idle problem

I have a 91 pickup with the 2.3 engine. The problem that you are having is likely the same problem I have - and it is caused by the Mixture Control Valve. It is a white plastic barbell shaped device in a holder on the inside fender wall. There are two vacuum hoses going to it - one small diameter and a larger one. Air enters the bottom of the valve and is drawn through the larger hose. The amount of vacuum on the small hose regulates the amount allowed through the large hose. I haven't found one at a parts store nor have I found one in a junk yard just yet. The Isuzu dealer can order one, but as the parts guy said, "Isuzu is very proud of their part". It costs about $150. If you want to check yours, there are several things you can do: first, run the vehicle and put your hand under the valve - it will **** a lot of air all the time. You can pull the valve off the truck and pry the bottom off the housing. You will probably see the same thing I did - broken pieces that used to stop the air flow through the valve. Until you get a replacement, you can try what I did: 1. Pull the small vacuum hose off and let it lay loose, or 2. Pull the small vacuum hose off and let it lay loose AND block the large hose (or the bottom of the valve). In either case, you have to adjust the fast idle screw and/or mixture screw on the side of the carburator. If you adjust either screw, write down what you did, in case you get a new valve later. The diference between 1 and 2 is that 1 will run good once it is warmed up but will want to stall until it warms; 2 runs good both when cold and warm, but will idle faster than it should. Neither of these will make the truck run like it should, but it is a 100 times better than trying to drive it with the loping.

Posted on Dec 13, 2009

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1990 isuzu pickup 4cl often will NOT idle at very low rpms/under 15 mph unless I ride the brakes/E-brake and gas at same time. I know for sure I have a cracked ( in two places) exhaust manifold. The...

this car EFI, or CARB, ill toss COIN, EFI gas.
what 4 cylinder, name it there are 7 used.
I'll now toss my coin land on GAS 4 cylinder engine. (in usa?)
is it racing too fast hot
or RPM too low hot.?

we cant guess what your statement above means.
the exhaust manifold cracks will cause the 02 oxy sensors to LIE,
to go lean (0volts ) this cause the fuel injection
to go RICH, (cause and effect closed loop rules)
and can idle too slow. (see that word SLOW)
the wrong word you used, after reading this vast times.

"NOT idle at very low rpms"
i decode this to mean?
NOt idle at proper low RPM (800 hot)
or spec 800 rpm , is more clear
that means the idle races hot.
this word is in all books on cars. engine RACES

IF true RACES it's not :
the exhaust crack, but can be if engine EFI slams in to limphome mode, do the flash codes show 12?
you never did those did you , bad idea skipping that. Google isuzu diagnostic jumper and read.
it's not he fuel tank ever,. not RACING.

what can cause any map based engine to race
well frankly LOTS:

but can be reduced to: (physics +)
1: throttle cables jammed. no slack. bad.
2: throttle valve jammed (gunk below it does that)(in the throttle body)
3: all vacuum leaks, (put huge list here, ask)
4: ISC or ICA valves stuck open
5: engine not reaching and holding 180f will cause #4 above to fail, naturally. bad thermostat. cause.
6: someone hacked your TB. (ask)
TB = throttle body.

vacuum leaks is an all day wall of text post
i refuse. but do have links to them.

Mar 12, 2017 | 1991 Isuzu Pickup

1 Answer

Truck sputters and doesnt have power at lower rpms

Possible fuel pump about to die. They will work if revs kept up

Aug 12, 2012 | 1990 Isuzu Pickup

1 Answer

Rough idle and blue smoke. change exhaust manifold because it was cracks know its missing and sputtering when i put in gear. changed egr valve before manifold.

blue smoke indicates either a bad transmission modulator valve,or a manifold leak{intake} i usually do this test for a bad or suspected bad intake manifold leak,light a cigarette and take it around the intake manifold and look for it to glow really bright for an intake leak,for an exhaust leak you can see it blow the embers away from it.just make sure there's no gas around to ignite.always make sure that a fire onsite! thank you for choosing!

Jun 09, 2011 | 1997 Nissan Pickup

1 Answer

Saber que es codigo 15 codigo 20 y codigo 25 isuzu trooper mod 1988 gasolina 2.600 cc. inyectado

Revise estos codigos correspondientes al sistema OBD I...

13 Open Oxygen Sensor Circuit
14 Coolant Temperature Sensor (High Temp Indicated)
15 Coolant Temperature Sensor (Low Temp Indicated)
21 Throttle Position Sensor (Signal Voltage High)
22 Throttle Position Sensor (Signal Voltage Low)
23 Manifold Air Temperature (MAT) Low Temp Indicated
24 Vehicle Speed Sensor (VSS) Circuit
25 Manifold Air Temperature (MAT) High Temp Indicated
32 EGR system fault
33 MAP sensor circuit (signal voltage high, low vacuum)
34 MAP sensor circuit (signal voltage low, high vacuum)
44 Oxygen Sensor Circuit (Lean Exhaust Indicated)
45 Oxygen Sensor Circuit (Rich Exhaust Indicated)
51 PROM error (faulty or incorrect MEM-CAL).


Apr 18, 2011 | 1987 Isuzu Trooper

1 Answer

1990 izuzu p/u 2.3 will start and run but will not idle?

Check all vacum hoses are not cracked ot split.If they are ok then replace the thotle air idler valve placed on the inlet manifold.Hope that has help you.Pippall.

Jun 10, 2010 | 1990 Isuzu Pickup

2 Answers

I have a 1991 Isuzu pickup that will not idle. What can I do?

The first two things to check are vacuum leaks on the motor, and lines that have busted or off, also may be a leaking intake manifold gasket. Also, the idle control, it can go out from time to time. Hope that gives ya good starting point. A good way to check the manifold gasket is to spray along the gasket and see if changes the rpms.

Jul 21, 2009 | 1991 Isuzu Pickup

1 Answer

Rough idle engine ticking

check for a lose spark plug lead or cracked elecrod insulation on spark plug

Jul 09, 2009 | 1990 Isuzu Spacecab

1 Answer

1990 isuzu pickup temp sender location

It is on the underside of the intake manifold near the front directly below where the water hose and thermostat connect on the top
Jack Boersema

Dec 16, 2008 | 1990 Isuzu Pickup

1 Answer

1990 holden rodeo /isuzu pick-up temp sender

from memory it is in inlet manifold some were in front middle section bottom, (underneath) 4ZE1?
single wire possibly yellow

Dec 16, 2008 | 1990 Isuzu Pickup

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