How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Tom Your Own Question

Tom
Tom, ASE Certified Technician
Category: Car
Satisfied Customers: 25356
Experience:  ASE Certified Master Technician
3827149
Type Your Car Question Here...
Tom is online now
A new question is answered every 9 seconds

95 isuzu rodeo has hesitation acceleration and wandering idle.

Resolved Question:

95 isuzu rodeo has hesitation acceleration and wandering idle.
Submitted: 2 years ago.
Category: Car
Expert:  Tom replied 2 years ago.
Most common are cracked intake manifold gaskets.Spray the intake manifold and see if the idle raises if so thats the issue this is very common let me know what you find.
Customer: replied 2 years ago.

After injectors were replaced, the mechanic sprayed in that area and found no leaks.

 

i did the same and found no change in rpm.

 

Another mechanic did a smoke test and found

small leak from the pcv grommet and it was replaced with new one.

Expert:  Tom replied 2 years ago.
Has the o2 sensor replaced?
Customer: replied 2 years ago.
no
Expert:  Tom replied 2 years ago.
Ok this will cause this code .If timing is fine you need to check the o2 sensor next and repalce it and also make sure the catalytic converter is not clogged.Has o2 sensor cause this exact issue .These are the next steps.Positive feedback and bonuses greatly appreciated.Last could be a faulty ECM.
Customer: replied 2 years ago.

Only code 12 stored.

Timing is 8-10BTDC.

Converter was checked at 2 muffler shops, not clogged.

Would not a defective o2 sensor show a code?

Expert:  Tom replied 2 years ago.
Yes it will give the code 12 and sometimes code 44 . This is either an o2 sensor issue or ECU issue . If compression is good start here next. Hoped this helped . Positive feedback and bonuses greatly appreciated.
Customer: replied 2 years ago.

One mechanic had checked compression but i think it was done on one cylinder.

 

I will check all 6.

 

Doesn't this engine require 4 o2 sensors.

Expert:  Tom replied 2 years ago.
Ok check compression and yes there are 4 sensors so test them before just repalcing them .
Customer: replied 2 years ago.

how should i test the o2 sensors?

 

 

Expert:  Tom replied 2 years ago.
With your meter or scanner.
Customer: replied 2 years ago.

I'll check the o2's tomorrow.

Thanks for your help.

Expert:  Tom replied 2 years ago.
anytime .Dont forget to click the green accept button so I can get credit for my help.You can add to the question for no further charge if you still need help.Positive feedback and bonuses greatly appreciated.
Customer: replied 2 years ago.

Sorry I have not replied to you sooner, did not mean to leave you hanging but I had family health issues that take priority.

Last time we talked you suggested checking the o2 sensor.

Results:

1) Original o2 sensor heater element showed no resistance; and real-time o2 output

measured at ECM was .020-.080v instead of .200-.900v, crossover was approx

1x /sec @750, 2x /sec @2000 rpm. Amplitude low but frequency good.

2) Checked circuit integrity of o2 heater and signal: good

3) Replaced o2 sensor with oem Denso.

4) New o2 sensor heater element measured 3.5-15ohms; and real-time o2 output

measured at ECM was initially .340V for 30 seconds then dropped to .020-.030V at

750rpm; .060V @2000rpm @45mph cruising at level, and .200-.720V @ 2000rpm cruising uphill.

5) Performed back pressure test utilizing the o2 sensor hole. There is only one o2 sensor

and it is located pre-catalytic converter.

Result was: 0.5psi @750rpm, 1.0psi @2500rpm, and 1.5psi with sudden throttle.

6) Final result: car performs with same symptoms of hesitation at partial throttle at any speed but not as bad. Car hesitates and stumbles then seems to clear up then strong acceleration.

Expert:  Tom replied 2 years ago.
OK this can be caused by a faulty ECU or the catalytic convertor is damaged and is the cause .I would have this checked again.Hope all is well with your family as thats what counts in this world.I would check these next .
Customer: replied 2 years ago.

1) Why is the o2 reading so low at idle, ex: .060v instead of .2-.8v.

2) I tested backpressure .5@ idle and 1.5@ sudden throttle. Isnt under 2.0

acceptable?

 

Expert:  Tom replied 2 years ago.
No that's why this is either a catalytic converter issue or ECU issue . These are what will cause this and need to be checked next. Hoped this helped. Positive feedback and bonuses greatly appreciated.
Customer: replied 2 years ago.
how do i check a faulty ECU?
Expert:  Tom replied 2 years ago.
Unfortunately it would need to be sent out and tested for about 75 to 100 dollars to test the printed circuit board inside.
Customer: replied 2 years ago.

I will take my car to where i bought the last convertor and have them check it tomorrow

morning and ill let you know what they found.

Thanks.

 

Expert:  Tom replied 2 years ago.
No problem . Don't forget to click the green accept button so I can get credit for my help. You can still add to the question for no further charge . Hoped this helped. Positive feedback and bonuses greatly appreciated.
Customer: replied 2 years ago.

I took the car in yesterday morning to check the condition of the converter and muffler.

1) They put it on the lift and found the converter and muffler to be good.

Isuzu spec states if 1 3/4-2.0psi @2000rpm backpressure that converter is plugged.

I'm getting .8-1.0 psi @2000rpm.

2) They noticed the connector to the MAP sensor had a broken locking tab and used

a tie wrap to secure the wires to the sensor mount. I took it for a test drive and 95%

of the hesitation problem was gone. Pulling away from a stop at low rpms it ran

strong. They suggested I check the integrity of the connector and wires.

3) Drove to a gas station to fill-up and on the way there were no problems. After restart

it went back to hesitation problems.

 

Expert:  Tom replied 2 years ago.
Ok if those map sensor wires are damamged theres a good chance its loosing its signal and its possible the map sensor is also shorting out.These need to be checked next.Hoped this helped.Positive feedback and bonuses greatly appreciated.
Customer: replied 2 years ago.

I subscribe to Mitchell1 and Alldata and I am presently downloading wiring diagrams

so that I can check the wiring harness this weekend.

 

I have not rated you yet because i thought as soon as i did it closes this thread and it

helps me by reviewing your answers.

 

 

 

Expert:  Tom replied 2 years ago.
No once you click accept you can continue for no further charge and I will continue with you .
Tom, ASE Certified Technician
Category: Car
Satisfied Customers: 25356
Experience: ASE Certified Master Technician
Tom and 8 other Car Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Excellent reply, and also very quick. Really sounds like the Expert knows what he is talking about. I will be back to use your service when I need more help with my RV. Dutch USA
 
 
 

Meet The Experts:

 
 
 
  • Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
< Last | Next >
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)

    Technician

    Satisfied Customers:

    846
    16 years of experience
  • http://ww2.justanswer.com/uploads/TE/TedG/2012-6-15_14759_avaLarge.64x64.jpg Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    1596
    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    1311
    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    ASE Master Tech

    Satisfied Customers:

    2367
    ASE Master Tech advanced level specialist
  • http://ww2.justanswer.com/uploads/SU/supermechanic/2013-8-23_03546_500.64x64.jpg Jerry's Avatar

    Jerry

    Master Mechanic

    Satisfied Customers:

    1906
    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    942
    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
  • http://ww2.justanswer.com/uploads/ST/Steve7654/2012-6-5_215929_japic800x660.64x64.jpg Steve's Avatar

    Steve

    Auto Service Technician

    Satisfied Customers:

    1980
    25+ yrs experience as a professional working technician; ASE L1 master technician