Hesitation at acceleration, idle less than 1rpm, poor gas milage

[achha64]

Hi,

I have a 97, 3.4l 4wd. I have around 123 000 miles.
The sparks plug have been replaced 5 months ago by Denso service center.

I start to notice since a month a that my baby hesitate and have a poor acceleration and really poor gas milage. The car idle around 0.5 rpm.

What should I check? Can the replaced spark plug be bad?
Fuel filter? Maf sensor? Engine oil? Injector?

Please share your experience.


Thank you

 

[tre9er]

any check engine light? If so, pull the codes and post them.

 

[achha64]

any check engine light? If so, pull the codes and post them.

No check engine light.

I'm thinking to replace the fuel filter at first and see what happen? What do you think? Sometime the cheapest can causes the biggest problems.

 

[tre9er]

Cleaning the MAF may help too, but be careful you do it right. Search here.

 

[achha64]

Cleaning the MAF may help too, but be careful you do it right. Search here.

Oh just remember that this problem happened after my 300 km trip with an open air filter box, with rain. I was checking the air filter and forgot to close it before the trip and discover it once arrived. So this can make the MAF dirty?

 

[tre9er]

Oh just remember that this problem happened after my 300 km trip with an open air filter box, with rain. I was checking the air filter and forgot to close it before the trip and discover it once arrived. So this can make the MAF dirty?

I'm sure it could.

 

[Jasonredwood]

I had a weird idle and poor MPG for the last couple months. MPG was around 14-16.
I cleaned the MAF, throttle body and the IAC which seemed to help for a few days. Then the idle issues and poor MPG continued. Finally threw a code calling for a bad AIC. I replaced the AIC and the TPS valve while I was at it. Idle is at 650 and the MPG is at 20-21 on the freeway now.

 

[achha64]

I had a weird idle and poor MPG for the last couple months. MPG was around 14-16.
I cleaned the MAF, throttle body and the IAC which seemed to help for a few days. Then the idle issues and poor MPG continued. Finally threw a code calling for a bad AIC. I replaced the AIC and the TPS valve while I was at it. Idle is at 650 and the MPG is at 20-21 on the freeway now.

Thanks, did you have an engine poor acceleration also?
What is AIC ?

Should I start to clean my MAF first or start scan code even if I don't have any check yet??

 

[TheeMikeB]

yep MAF is a good start, to trouble shoot you an just disconnect it and see if the hesitation smooths out. If it does that's your culprit, if not prob isn't. Easy to clean with some MAF sensor cleaner. Just pull /spray/replace. Job should take no more than 5 min tops.

 

[JRZEE2000TR4LTD]

Thanks, did you have an engine poor acceleration also?
What is AIC ?

Should I start to clean my MAF first or start scan code even if I don't have any check yet??

It's IAC- Idle Air Control Valve. It basically controls the air mixture coming in while the throttle body butterfly is closed, which is when the truck is started and when the vehicle is idling. Symptoms of IAC problems include ,hard starting or non starting, rough idle, rich or lean condition (depending if the valve is stuck open or shut) May or may not throw a CEL.

 

[achha64]

It's IAC- Idle Air Control Valve. It basically controls the air mixture coming in while the throttle body butterfly is closed, which is when the truck is started and when the vehicle is idling. Symptoms of IAC problems include ,hard starting or non starting, rough idle, rich or lean condition (depending if the valve is stuck open or shut) May or may not throw a CEL.

My car start like new. In cold or whatever situation. I just need to plug the key and turn and Boom car start. So no start problem at all. Just a hesitation acceleration, and low RPM at idl.

 

[JRZEE2000TR4LTD]

My car start like new. In cold or whatever situation. I just need to plug the key and turn and Boom car start. So no start problem at all. Just a hesitation acceleration, and low RPM at idl.

Then clean the MAF first. See if that helps especially since you left the air filter housing open. The IAC could affect acceleration if it were sticking open and causing a lean condition. (too much air in your air/fuel mixture) although I believe a CEL would probably occur with that.

Is .5 rpm 500 rpms?

 

[achha64]

Then clean the MAF first. See if that helps especially since you left the air filter housing open. The IAC could affect acceleration if it were sticking open and causing a lean condition. (too much air in your air/fuel mixture) although I believe a CEL would probably occur with that.

Is .5 rpm 500 rpms?

Yes it's 500 rmps. Its seem too low for me. I used to see it around 800 RPMS.
No CEL at all! Maybe a Scan can give me I want to know.

I just suspected the MAF Airflow, and the Fuel Filter.

Ive been cleaning the Throttle bottle by Denso Service Center with their special cleaner the same time that I changed the Spark plugs (4 months ago).

This is the only problem that I have with this baby, except this, this bad boy rock like god. The ride would be comfy for me if I have a better acceleration.

 

[Jasonredwood]

Yeah I meant IAC. Autocorrect on my phone defaults to 'AIC'.

I agree with starting at the MAF cleaning. Not sure if you can pull a code with out a CEL. I doubt it.

I had a high idle, around 1100-1500, then it would drop to 400-500 for no reason that I could see. Then back up again.

The final fix for me was the IAC. idled at 650 after the new OEM.

 

[JRZEE2000TR4LTD]

Yeah I meant IAC. Autocorrect on my phone defaults to 'AIC'.

I agree with starting at the MAF cleaning. Not sure if you can pull a code with out a CEL. I doubt it.

I had a high idle, around 1100-1500, then it would drop to 400-500 for no reason that I could see. Then back up again.

The final fix for me was the IAC. idled at 650 after the new OEM.

He's also complaining about poor acceleration, which could be attributed to the IAC. Did you have an acceleration issue? Just curious.

 

[achha64]

He's also complaining about poor acceleration, which could be attributed to the IAC. Did you have an acceleration issue? Just curious.

I have yes! its hard to explain like this.

When the car is Cold, the RPMS is really hight around 1500 on idl. I think it's normal for this. The acceleration is poor let say on the first gear. Hesitation, hard, RPM goes around 1500 but not much acceleration just the V6 noise and then its okay the RPM come down to 1200 or 1000.

Engine seem to force a lot to accelerate the first gear. Poor acceleration.

 

[JRZEE2000TR4LTD]

I have yes! its hard to explain like this.

When the car is Cold, the RPMS is really hight around 1500 on idl. I think it's normal for this. The acceleration is poor let say on the first gear. Hesitation, hard, RPM goes around 1500 but not much acceleration just the V6 noise and then its okay the RPM come down to 1200 or 1000.

Engine seem to force a lot to accelerate the first gear. Poor acceleration.

I was asking Jasonredwood if he had acceleration issues when he replaced his IAC.

 

[Jasonredwood]

He's also complaining about poor acceleration, which could be attributed to the IAC. Did you have an acceleration issue? Just curious.

Yeah I did have an acceleration issue. Meant to respond to that but got sidetracked. From a stop the hesitation was very noticeable.

 

[trdsport]

Yeah I did have an acceleration issue. Meant to respond to that but got sidetracked. From a stop the hesitation was very noticeable.

Hey folks..where is this IAC located. I have been having the same issue of hesitation as well ?