'92 Isuzu Rodeo 3.1L V6 is unhappy

Use this forum to test posting messages and pictures before posting on the actual forum. If you are a new user, this is a great place to learn how to post

'92 Isuzu Rodeo 3.1L V6 is unhappy

Postby Marie » Tue Sep 17, 2019 6:31 pm

243,000 miles, two-wheel drive, regularly and lovingly maintained since new by same owner but all work is done by technicians. I frequently reference my 1989 - 2002 Haynes Repair Manual to keep up with work that is done, sticking to the recommended Isuzu mainteneance schedule since new. In last couple years, it chokes back intermittently when I accelerate, coughing (no backfire) as if it can't breathe. Check engine light comes on intermittently. Technician just replaced fuel filter, air filter, spark plugs, distributer cap & rotor, replaced coil (ignition timing), cleaned EGR valve, flushed power steering fluid, fuel pressure test. Technician not sure what to do next. Any suggestions ?
Marie
Drives on Pavement
 
Posts: 3
Joined: Tue Sep 17, 2019 5:55 pm
Has thanked: 0 time
Have thanks: 0 time

Sponsor
 

Re: '92 Isuzu Rodeo 3.1L V6 is unhappy

Postby Ed Mc. » Thu Sep 19, 2019 2:21 am

Marie wrote:243,000 miles, two-wheel drive, regularly and lovingly maintained since new by same owner but all work is done by technicians. I frequently reference my 1989 - 2002 Haynes Repair Manual to keep up with work that is done, sticking to the recommended Isuzu mainteneance schedule since new. In last couple years, it chokes back intermittently when I accelerate, coughing (no backfire) as if it can't breathe. Check engine light comes on intermittently. Technician just replaced fuel filter, air filter, spark plugs, distributer cap & rotor, replaced coil (ignition timing), cleaned EGR valve, flushed power steering fluid, fuel pressure test. Technician not sure what to do next. Any suggestions ?


Hi, Marie, Welcome to the Planet! Your GM 3.1 V6 is a pretty reliable Stone-Age Iron Beast, but there are common issues that crop up, especially with hi-mileage engines. One very common issue is timing chain stretch. Usually the chain stretches which changes the cam timing, eventually it becomes very sloppy and can even break. The timing "damper" that sits in the middle of where the chain runs, has rubber "slipper shoes" bonded to its metal frame. The rubber gets old, hardened, and sometimes breaks. Then the chain rides on the metal, causing havoc.

Your mechanic can check for a sloppy timing chain by rocking the crankshaft pulley back and forth while watching the distributor rotor. If there is a lot of lost motion between when the crankshaft moves and the rotor moves (there should be none), the timing chain is stretched.

But since the engine computer (ECU or ECM) is setting a trouble code, your mechanic should be reading that to find out what code is set. It might point to a solution.

Note that there's a specific way to check timing, there's a wire in the center console called the EST (Electronic Spark Timing) wire. This wire must be unplugged from itself (it's got an inline connector) before trying to read the timing. Long as the mech. has done this, timing should be ok. Factory setting is on the decal on the underside of the hood, probably about 10 degrees BTDC (Before Top Dead Center).

Mech. should also check the (2) fuel injectors in the throttle body for proper spray pattern. If the injectors are partially clogged, that's going to cause a lean condition and a "bogging" problem. There should be a full, fan-shaped spray coming out of each injector. Any dribbles or missing segments of spray indicate problems. I'd recommend rebuilt injectors if they require replacement, Rockauto.com is one good source for those. Or eBay. Any number of companies "rebuild" these by cleaning, reassembling and flow-checking. Good as new!

Another pesky problem I've had (and many others here) in the past, is failure of the Engine Coolant Temperature sensor (ECT or aka ECS). When this happens, the engine will run poorly if at all. This sensor screws into the middle of the intake manifold, just forward of the TBI (Throttle Body Injection) unit. It's easy to replace, with a cooled-down engine you don't even need to drain the radiator.

A very easy way to rough-diagnose this sensor is to unplug it. This of course will set a "check engine" lite and trouble code. If the engine runs better, the sensor is definitely perished. It's not gonna run real sharp but if your symptoms are different, likely it's an issue. The sensor can be checked for proper resistance at a given temperature, with an ohmmeter.

A few other things that come to mind are O2 sensor (cheap to replace); restricted exhaust system (pressure checks can be done); distributor ignition module. The ign module in the distributor runs very hot and if the heat sink compound between the module and the distributor dries out, the module gets hot and can act up or fail. This heat sink stuff is similar to what's used on computer CPU's (like Arctic Silver, etc).

FIY here's a link to Rockauto.com parts for your '92 Rodeo:

https://www.rockauto.com/en/catalog/isu ... v6,1176881

BTW, you may get more help if you post in the "Drivetrain Problems" section, there's a ton more traffic there than in this "test" section.

Or, HEY MODS, maybe you can just move this thread, eh? That would be cool! :idea: :mrgreen: :twisted:

HTH & let us know how things work out..............ed
You do not have the required permissions to view the files attached to this post.
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
Ed Mc.
I am the Stig
 
Posts: 4256
Joined: Thu Aug 14, 2003 1:26 am
Location: Poulsbo, WA
Has thanked: 7 times
Have thanks: 407 times

Re: '92 Isuzu Rodeo 3.1L V6 is unhappy

Postby Marie » Thu Sep 19, 2019 10:33 am

Thrilled to see your considered & thorough response, Ed ! !
If there is timing change stretch, will I be able to hear it during idle or while driving ? If it is audible, where will it come from ?

My mechanic has read the code on two different occasions - he thought the last "fixes" which I referenced in my initial post, may correct my issue. But, alas ! This last "read" pointed to either fuel pressure or exhaust issues. (I lost my dealer mechanics 1982ish when the dealership dropped the Isuzu line & I have had to make several changes since then) My mechanic is new to my vehicle, but seems generally knowledgable & willing to focus on my problem.

You reference 2 fuel injectors but I am confused as to why I'm told that my carbureted engine is not a fuel-injected engine. I was billed for cleaning fuel injectors at 85,000 mi (using 3 part B.G. cleaner system) & thought I may have been duped. Does RockAuto give a warranty ? Mechanic will order only from his sources due to lack of warranty on some of these suppliers.

I will address each of your other suggestions..many thanx.

Thank you for the suggestion to post in the DriveTrain section. I wasn't sure where to go after this initial post. Can I move this conversation to that location or do I need to start over ?
Marie
Drives on Pavement
 
Posts: 3
Joined: Tue Sep 17, 2019 5:55 pm
Has thanked: 0 time
Have thanks: 0 time

Re: '92 Isuzu Rodeo 3.1L V6 is unhappy

Postby Ed Mc. » Thu Sep 19, 2019 8:14 pm

Marie wrote:Thrilled to see your considered & thorough response, Ed ! !
If there is timing change stretch, will I be able to hear it during idle or while driving ? If it is audible, where will it come from ?

My mechanic has read the code on two different occasions - he thought the last "fixes" which I referenced in my initial post, may correct my issue. But, alas ! This last "read" pointed to either fuel pressure or exhaust issues. (I lost my dealer mechanics 1982ish when the dealership dropped the Isuzu line & I have had to make several changes since then) My mechanic is new to my vehicle, but seems generally knowledgable & willing to focus on my problem.

You reference 2 fuel injectors but I am confused as to why I'm told that my carbureted engine is not a fuel-injected engine. I was billed for cleaning fuel injectors at 85,000 mi (using 3 part B.G. cleaner system) & thought I may have been duped. Does RockAuto give a warranty ? Mechanic will order only from his sources due to lack of warranty on some of these suppliers.

I will address each of your other suggestions..many thanx.

Thank you for the suggestion to post in the DriveTrain section. I wasn't sure where to go after this initial post. Can I move this conversation to that location or do I need to start over ?


Timing chain may or may not make noise. You'll sure know if it breaks! :twisted: Best way to quickly check for wear is by doing the "free play" thing previously mentioned.

Yes, indeed, the GM 3.1 is fuel-injected. If you pop the air cleaner lid you'll see the (2) fuel injectors in a "pod". You can watch the spray pattern while the engine is running, although if you hook up a timing light, the stroboscopic action will "freeze" your view of the spray pattern and maybe make it easier to see. Attached are a couple of pics of a typical GM TBI. They're pretty simple to begin with, and the TBI system is generally easy to troubleshoot. They can make a lot of power, too, as the hot-rodded Camaro 3.4 engine in my '90 Trooper will attest!! :mrgreen:

Here's a list of moderators, just click on one of their names and on the resultant page you'll see a link for "send private message". Just ask if they'll move the thread to Drivetrain Problems, the most appropriate forum for your issues.

https://forum.planetisuzoo.com/memberli ... =group&g=3

BTW an excellent fuel cleaner is Gumout Regane. The Hi-Miles stuff has a bit of top-end lubricant. Regane has a high level of PEA solvent, which is a very good carbon cleaner. A bottle in the fuel for a couple of tanks can't hurt.

https://www.walmart.com/ip/Gumout-Regan ... W/16888905

I've had good luck with Rockauto, their parts do come with the mfr's warranty, and they are pretty good on returns if you get a bum part. I had a new set of Power Stop performance discs for my daughter's Toyota, and something was wrong with the way they were machined. They tore up the brake pads as soon as the car was moved. I contacted Customer Service with pics of the problem, and they did an RMA with no hesitation. Even paid for the return shipping. You've got to watch their shipping charges, because not every item comes from the same warehouse; so you can stack up charges pretty fast if the parts you order come from all over. Other than that, their prices are pretty good and generally the shipped price is very competitive. Plus they have numerous closeout/wholesale deals that are ridiculously cheap. When you're looking at parts there, click the "Info" button next to the part and a detailed description page will popup. You'll find any warranty info there, too.

Anyway, hope that helps clear things up a bit...........ed
You do not have the required permissions to view the files attached to this post.
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
Ed Mc.
I am the Stig
 
Posts: 4256
Joined: Thu Aug 14, 2003 1:26 am
Location: Poulsbo, WA
Has thanked: 7 times
Have thanks: 407 times

Re: '92 Isuzu Rodeo 3.1L V6 is unhappy

Postby Marie » Fri Sep 20, 2019 2:31 pm

Thank you kindly for your inciteful response & accompanying clips; I'm grateful for all the info I can get.
Eunice
Marie
Drives on Pavement
 
Posts: 3
Joined: Tue Sep 17, 2019 5:55 pm
Has thanked: 0 time
Have thanks: 0 time


Who is online

Users browsing this forum: No registered users and 2 guests