90 Trooper Engine Stumbles

This forum is for the discussion of general Isuzu related information

Moderator: Staff

90 Trooper Engine Stumbles

Postby AthensSuperTrooper » Thu May 20, 2010 10:32 pm

Hey guys I have been having this problem for the past month. First off I have a 90' 4 cyl Trooper 4x4. It has been running great up till about a month ago. The symptom is whenever the engine is under load going up a hill (Mostly) it, for a lack of a better word, "stumbles". If I sit in neutral and just gas the engine is purrs like a kitten no backfires, stumbles, etc.., but as soon as go down the road at around about 3rd gear + the engine slightly stumbles. Now this does not always happen. Some times I have to really race the engine up the hill to get it to stumble other times if I am in a high gear it will stumble even if I am on a slight incline.

My mechanic believes that its a fuel/O2 delivery issue and I agree. We've replaced vacuum lines and looked for leaks, put in a new gas filter (which it needed), added fuel treatment for possible moisture in tank and cleaned injectors + added a new O2 sensor. The Sensor actually had come loose the week I took it to my mechanic, he replaced it with a new one and I saw improved engine performance, but the issue with stumbling still lingers. After all of this work the little truck runs great, but it is still stumbling ever so slightly which is a lot less then it did when I first brought it into the shop.

Does anyone else have a clue what could be the issue? I am getting a new MAF sensor tomorrow and crossing my fingers.


Thanks for the help guys
90' Trooper 4cyl
User avatar
AthensSuperTrooper
Drives on Pavement
 
Posts: 9
Joined: Thu May 20, 2010 10:11 pm
Location: Athens Ga
Has thanked: 0 time
Have thanks: 0 time

Sponsor
 

eng

Postby 5 th rodeo » Thu May 20, 2010 10:36 pm

How many miles on your spark plugs, as a spark plug will fire perfect with no presure, but when under a load they will fail if they are weak.
5 th rodeo
Expedition Ready
 
Posts: 979
Joined: Tue Feb 16, 2010 10:16 pm
Location: scottsdale, az
Has thanked: 0 time
Have thanks: 44 times

Postby shooter » Thu May 20, 2010 10:37 pm

Dist cap, rotor, plug wires, plugs? Coil?
1989 Isuzu Trooper S/ 4WD / 2.6 Litre 4 Cyl 4ZE1 Converted to Weber 32/36 Carb / 5-speed Manual (MUA5) / Warn Premium Hubs / Fancy Radio / Deluxe Intermittent Combination Wiper Switch

I'd rather laugh with the sinners than cry with the saints

Some people are like Slinkies; they are not good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
User avatar
shooter
Donor
Donor
 
Posts: 11704
Joined: Sun Mar 30, 2008 7:49 pm
Has thanked: 38 times
Have thanks: 149 times

Postby AthensSuperTrooper » Thu May 20, 2010 10:41 pm

shooter wrote:Dist cap, rotor, plug wires, plugs? Coil?


All of that is fairly new. Although I think the plugs have over 10k miles on them.
90' Trooper 4cyl
User avatar
AthensSuperTrooper
Drives on Pavement
 
Posts: 9
Joined: Thu May 20, 2010 10:11 pm
Location: Athens Ga
Has thanked: 0 time
Have thanks: 0 time

Postby shooter » Thu May 20, 2010 10:47 pm

How were the injectors cleaned? One or more of them may be worn. This place has a good reputation here and is provided for future reference.

http://www.witchhunter.com/
1989 Isuzu Trooper S/ 4WD / 2.6 Litre 4 Cyl 4ZE1 Converted to Weber 32/36 Carb / 5-speed Manual (MUA5) / Warn Premium Hubs / Fancy Radio / Deluxe Intermittent Combination Wiper Switch

I'd rather laugh with the sinners than cry with the saints

Some people are like Slinkies; they are not good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
User avatar
shooter
Donor
Donor
 
Posts: 11704
Joined: Sun Mar 30, 2008 7:49 pm
Has thanked: 38 times
Have thanks: 149 times

Postby caveman » Thu May 20, 2010 11:16 pm

Don't I repeat DON'T buy that mafs. It's not your problem. Your better off making a donation to the planet to get your truck back up to par then buying that part. Your just throwing your money away.

Pull the distributor cap and check the center black button. It should have a rounded top with only slight flattness wear on it, also it should stick out about 1/8th of an inch and have a springyness to it when you push on it. Also don't bother testing the rotor (screwed onto the distributor shaft) just go get another one. The rotor has a resistor built into it (your can't see it but it's in there trust me). It supresses any radio interference that might occur when a high tention static discharge occurs in the vehicles electrical system (ignition coil, plugs) Sometimes the resistor is cheaply made and cannot handle the high power of the 2.6's coil pack. Also most importantly, your plug wires will leak and cause your exact symptom because one of your plug wires are not delivering enough of the spark energy to detonate the rich mixture in the combustion chamber that occurs when your accelerating. 3rd,4th and 5th gear taxes the engine under acceleration more then 1st or 2nd.

Either test your plug wires with an ohm meter and check for either high ohm readings across the board or for one wire that is way out of spec.

Also an ohm meter doesn't check for a bad insulator on any given wire. It only checks the health of the graphite core.

So to check the health of the insulator you'll have to look under the hood in an EXTREMELY dark area to see any arching. Use your periphreal vision to check for minute sparks. You may not see a little lightning bolt (like a spark plug) but more so a series of blue static waves running between the wire and ANY other object.IE; rubber hoses, body, eninge parts. You'll have to rev the engine to really get down to the nitty gritty but you'll find that 80% of all "cheap" brands of wires out in the world right now have some degree of leakage. Wires are not something that you want to spend cheap on.

Start here and get back to me, I have some other Ideas too.

Good luck!
Image
1988 to 98 Isuzoo Trooper II. rebuilt with american pride! Built and tested now parked and resting until the next adventure!
User avatar
caveman
Almost Joe Isuzu
 
Posts: 2672
Joined: Thu Mar 05, 2009 8:42 am
Location: midwest/eastcoast guy USA
Has thanked: 10 times
Have thanks: 34 times

Postby AthensSuperTrooper » Thu May 20, 2010 11:28 pm

rollintroopers wrote:Don't I repeat DON'T buy that mafs. It's not your problem. Your better off making a donation to the planet to get your truck back up to par then buying that part. Your just throwing your money away.

Pull the distributor cap and check the center black button. It should have a rounded top with only slight flattness wear on it, also it should stick out about 1/8th of an inch and have a springyness to it when you push on it. Also don't bother testing the rotor (screwed onto the distributor shaft) just go get another one. The rotor has a resistor built into it (your can't see it but it's in there trust me). It supresses any radio interference that might occur when a high tention static discharge occurs in the vehicles electrical system (ignition coil, plugs) Sometimes the resistor is cheaply made and cannot handle the high power of the 2.6's coil pack. Also most importantly, your plug wires will leak and cause your exact symptom because one of your plug wires are not delivering enough of the spark energy to detonate the rich mixture in the combustion chamber that occurs when your accelerating. 3rd,4th and 5th gear taxes the engine under acceleration more then 1st or 2nd.

Either test your plug wires with an ohm meter and check for either high ohm readings across the board or for one wire that is way out of spec.

Also an ohm meter doesn't check for a bad insulator on any given wire. It only checks the health of the graphite core.

So to check the health of the insulator you'll have to look under the hood in an EXTREMELY dark area to see any arching. Use your periphreal vision to check for minute sparks. You may not see a little lightning bolt (like a spark plug) but more so a series of blue static waves running between the wire and ANY other object.IE; rubber hoses, body, eninge parts. You'll have to rev the engine to really get down to the nitty gritty but you'll find that 80% of all "cheap" brands of wires out in the world right now have some degree of leakage. Wires are not something that you want to spend cheap on.

Start here and get back to me, I have some other Ideas too.

Good luck!






Thanks bud thats some solid help. I will hit that up with my mechanic tomorrow!
90' Trooper 4cyl
User avatar
AthensSuperTrooper
Drives on Pavement
 
Posts: 9
Joined: Thu May 20, 2010 10:11 pm
Location: Athens Ga
Has thanked: 0 time
Have thanks: 0 time

Postby AthensSuperTrooper » Fri May 21, 2010 11:08 pm

rollintroopers wrote:
Start here and get back to me, I have some other Ideas too.

Good luck!




Thanks man! You had it correct this was my problem. My Super Trooper is back in business. You saved me 160 bucks which is what a local import shop would have charged me just to put it up on diagnostics. I forwarded your advice to my mechanic and he hooked it up. Thanks again bud, I owe ya one.
90' Trooper 4cyl
User avatar
AthensSuperTrooper
Drives on Pavement
 
Posts: 9
Joined: Thu May 20, 2010 10:11 pm
Location: Athens Ga
Has thanked: 0 time
Have thanks: 0 time

Postby shooter » Fri May 21, 2010 11:32 pm

What was the problem?
1989 Isuzu Trooper S/ 4WD / 2.6 Litre 4 Cyl 4ZE1 Converted to Weber 32/36 Carb / 5-speed Manual (MUA5) / Warn Premium Hubs / Fancy Radio / Deluxe Intermittent Combination Wiper Switch

I'd rather laugh with the sinners than cry with the saints

Some people are like Slinkies; they are not good for anything, but they still bring a smile to your face when you push them down a flight of stairs.
User avatar
shooter
Donor
Donor
 
Posts: 11704
Joined: Sun Mar 30, 2008 7:49 pm
Has thanked: 38 times
Have thanks: 149 times

Postby krlanga » Sat May 22, 2010 11:38 pm

shooter wrote:What was the problem?


x2, what was the problem?
Krlanga®
88's Tropper LS
2.6L I-TEC 4ZE1
31x10,5r15 Maxxis Bighorn
15x8" US Wheels rims

Image
User avatar
krlanga
Rodeo King
 
Posts: 187
Joined: Thu May 29, 2008 8:30 pm
Location: Concepción, Chile
Has thanked: 0 time
Have thanks: 0 time

Postby AthensSuperTrooper » Sun May 23, 2010 1:17 am

The problem was what I originally posted about the stumbling engine. The fix was posted by rollintroopers:

Pull the distributor cap and check the center black button. It should have a rounded top with only slight flattness wear on it, also it should stick out about 1/8th of an inch and have a springyness to it when you push on it. Also don't bother testing the rotor (screwed onto the distributor shaft) just go get another one. The rotor has a resistor built into it (your can't see it but it's in there trust me). It supresses any radio interference that might occur when a high tention static discharge occurs in the vehicles electrical system (ignition coil, plugs) Sometimes the resistor is cheaply made and cannot handle the high power of the 2.6's coil pack. Also most importantly, your plug wires will leak and cause your exact symptom because one of your plug wires are not delivering enough of the spark energy to detonate the rich mixture in the combustion chamber that occurs when your accelerating. 3rd,4th and 5th gear taxes the engine under acceleration more then 1st or 2nd.
90' Trooper 4cyl
User avatar
AthensSuperTrooper
Drives on Pavement
 
Posts: 9
Joined: Thu May 20, 2010 10:11 pm
Location: Athens Ga
Has thanked: 0 time
Have thanks: 0 time

Postby ga trooper » Mon May 24, 2010 12:25 am

Most of the time whenever these 4 cyl's act up just replace the cap, rotor, plugs and adjust the valves and you will fix it. My 86 pickup died in downtown Athens back during my college years due to the center probe on the cap completely melting off due to wear. Had to walk to parts store and get stuff. My date wasn't happy. She still married me though 5 years later. Ha!!
88 Trooper 2.6 AW-30/80 auto w/manual t-case, 33's 3in. susp. 3in. body Warn 8274, 5.38's and aussie lockers. Revo T-Case gears, 4ZE1/ZD1head,+.020, balanced,Jet computer, York On Board Air, Other stuff
94 Trooper LS, auto OME stuff 929's and all shocks, Sway a Way bars, HD tie rods, BFG's.
91 Amigo 2.6 stock, busted head at the moment...
"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety."
--Benjamin Franklin
ga trooper
Has a Trail Truck
 
Posts: 335
Joined: Sun Mar 30, 2008 5:49 pm
Location: Dallas, Ga.
Has thanked: 1 time
Have thanks: 7 times


Return to General Isuzu Discussion

Who is online

Users browsing this forum: Google [Bot] and 15 guests