fabian15

Hi Guys! I've been a silent observer for a while now but, I have finally joined the club! And boy does it feel good!

I know that this has been covered a million times but, I feel like it helps me to write things down. Stone me if thou wilt! My hope is maybe you'll catch something I've missed.

The first time I noticed this was on a date (hehe) in the summer. The gas light was on but not completely empty (I wanted to see how far I could make it on empty!) it acted like it was about to run out of gas but then it went back to normal and I filled up at the next gas station. Surprisingly, she was cool with pushing if it came to it LOL. And it’s progressively getting worse. I used to get around 250 mpg and now it’s getting 150.

So, I've been searching the internet for the past couple months now trying to chase down this gremlin but I can't seem to nail it down. My truck is running rich when it is up to temp. When I first start it up it runs fine but when it goes to close loop (if it actually goes into close loop I’m still unsure of), all hell breaks loose. The idle will be bouncing between 300-1000 rpm. Sometimes, the motor bogs down so much that if throttle is applied, it will die. After about 15 seconds it will clear back up and be drive-able again.

Though my journey of google, I've found that there could be a number of problems. One by one been checking them. The first thing I checked was the IACV. It seemed good I cleaned it up and replaced those corroded coolant lines leading to it. I replaced the O2 sensor and PCV valve with no change. I pulled, cleaned, and tested the mass air flow sensor and everything was to spec. I pulled the throttle body to clean it and check the position sensor. Once again, it was in spec (I developed a sticky idle after I re-installed it probably due to the dash pot...). I then burped the coolant system with no change. I replaced the air filter, still no change. I pulled the EFI fuse to reset the computer, and it got better but, has recently come back. So this makes me believe that it is a sensor. The sensors I would like to check are the ECU temp sensors. Know how to check the lower one but I have no idea on the upper one. It is the 4x4 model so it has the rounded discontinued sensor. Other things I need to check are the cold start injector, the fuel pressure, fuel pressure regulator, spark plugs and wires (changed them 2 years ago). I think that's it, from what I can remember of my studies.

Any help would be appreciated! I'm in school right now and I hate being embarrassed by the ladies riding in my truck when it starts to act up

wyoming9

iTrader: (1)

How many miles have you driven since the plugs were changed you say two years ??

Sounds like a good tune up might be in order being most tune up parts are made in China the quality is some what lacking .

I am curious just what your plugs look like .

I think if the check engine light was on you would have mentioned it.

A low voltage condition can cause some interesting things to happen with the ECU

fabian15

I've only done maybe 4000 miles in the past 2 years.
you are correct there has been no check engine light.
I've been trying to use quality parts as often as i can. the plugs are nkg and the o2 is denso. i have yet to pull the plugs but i am curious to see them too.
I imagine that the O2 sensor is the main place to check for voltage drop?

Terrys87

iTrader: (1)

Start with a complete tune up. You could be chasing your tail over something simple. With it reving up and down, may need to burp the system. I raise the front end high and let it idle for about 15 minutes to get the air out of the system.

Running on empty can burn up your fuel pump. Gas keeps the pump cool. I fill up at 1/4 and start freaking out at the 1/8th tank mark.

I think the voltage will be to low to get a reading or I never could in the past so may be wrong on that. Probably has never been changed so would just replace it with a Denso, get a direct fit and not a generic.

MSR

Check the maf door for smooth operation

wyoming9

iTrader: (1)

Everyone of the 22R series engines I ever worked on get a tee in the heater hose by the heater valve.

remove the cap of the tee fill coolant all the air gets pushed out .

When the coolant level gets to the tee put the cap back on.

What I meant by low voltage is the whole system voltage dropping to low.Can cause the ECU to act strange.

Could be the throttle linkage hanging up on the throttle body or the other end where the cable attaches to the pedal.

I have to agree a good tune up never hurts