Posted: Apr 04 2008 at 5:23pm | IP Logged

Hello, back in NOvember I had a fuel line treatment at Walmart to clean my injector and since then I have lost 6 mpg. was at 21/16 now 16/11. It has gotten worse and worse and I was told to chech my MAF. My MAF was tested at the Garage and it was reading at the very top range of the allowed specs. I had it read by another garage and they confirmed the high reading.

Another suggestion I had was to clean the Throttle Body, which I did this past weekend. When I got to the TB, the carbon was so bad around the flap, and the body wall, that the flap did not appear to opperate correctly, like it was not able to close. I cleaned it throughly, some with the vehicle running, and some without it running. When I put the air flow parts back on, which was basically a plastic housinge that took the air from the filter past the MAF, to the TB, The truck ran terrible. I let it idle for a bit, and the Idle was very high, and when I would rev it it would stay at the top of the rev, like it was stuck. Also the check engine light was on. I used some SeaFoam two nights ago and it is still running terrible. It lurchs and pulsses when I drive it now!

I went to the local auto parts store, had them check the code, and they said it was the MAF or some other sensor and my Idle Control valve. It said the MAF was low voltage and the ICV Was  off and the truck idle was too high. They cleared it out, and the light stayed out for a day or so. Last night, it came back. I am going to get another check to see if its the same problem, but I know it will come back.

Now, I dont understand how cleaning the TB could have tripped the MAF, I went no where near it. Could I have messed up something spraying the TB Cleaner into the TB?

Also, my mileage still is in the tank. No change! DANG NABIT, that is the problem I have is I can't just let this go. The vehicle is not running right! I am to the point where I am ready to trade the truck that I love in, because I can't figure this out. I was getting good mileage before the service in Nov. By then we are already in winter fuel, so I do not think that is it.

I am now concerned not only for the piss poor mileage, but now the really bad way it idels and runs. Could I have messed up the idle control thing when I cleaned the Throttle body? I can't see how, but maybe I did. I don't know. I look for the smart people here for help!

I stated before, if someone can help me solve this, I will send them a box of cigars or their favorite beverage! HELP.

Posted: Apr 04 2008 at 6:43pm | IP Logged

I had a tapping in the motor on acceleration, went something like this vroooommmmmmmm (25 mph) ratatatatatatatta shift, vrooommmmmmmmmm (40) ratatatatatatatatatatat shift

I was trying to eliminate that, the mechanic at the Nissan Garage said I may have some predetonation with something sticking, so Walmart had a fuel line service that cleans the carbon out. They disconnected the Brake vaccuum line and went in there, but what I am finding is that it went all the way through my upper intake system as I had carbon on my airfilter. The carbon wa so bad on my Throttle Body I had to wipe it out, the spray cleaner would not move it.

WHat I think is that since they went into the engine where they did (rear right of engine compartment) that they went in and blew all that crud up into the upper intake system pushing it in the direction that the parts were not meant to see things.

The mileage dropped right away, the garage was no help, said it was winter fuel to move on, but I was running winter fuel and it was ndoing fine, so I knew that wa not it. The rough idle is now just from when I cleaned the TB and since then the check engine light is on. It is reading Idle control so I know thats it, but have no idea where it is. I have a manual on the truck I have on ebay so I can look there.

Problems right now are that I need to get it run right, the lunging forward when I stop and in gear is obviously not right. The mileage I think will auto adjust here once I get on these other issues.

Posted: Apr 04 2008 at 11:30pm | IP Logged

..

mastdog

...  Over the years I have seen quite a few times that a small piece of carbon has lodged in the gap of a spark plug causing zero firing. Carbon can also foul up the injectors causing a high RPM power miss. Carbon coated spark plugs will not idle very well.

You may have a knock sensor problem or EGR carboned up and not working correctly.

Here in the DFW area the 10% Ethanol is lowering our gas mileage 4 to 8%.

Posted: Apr 05 2008 at 7:01pm | IP Logged

Well I pulled the spark plugs that I could get to, only 4. Now with my luck the 2 I did not get to are the issue, but the other 4 were fine.

I have no idea where the other things you mentioned are, I will have to get out my manual to check it out.

Thanks for the replay, here in Pa we don't have any of the ethonal crap, but winter mix is just as bad.

I will continue my search for the anwser.

Posted: Apr 06 2008 at 8:20pm | IP Logged

Boomer wrote: Mastdog, I live in eastern PA (Lancaster) and ALL of our stations here have ethanol signs on them.  My son lives in State College and the last time I was up there they also had ethanol signs on the pumps as did stations in the Altoona area.

I don't recall seeing that anywhere I will take note next visit to the pumps.

I was doing some research on my problem in my manual and I did an idle air intake adjustment and a stopped air intake  adjustment as well as a throttle pedel adjustment. All of them I did from inside the truck. Now, the idle and lunging seems to have been corrected, I sure hope, and the idle is below 1 on the tach now, where it used to be.

Posted: Apr 09 2008 at 6:50pm | IP Logged

mastdog wrote: at Walmart to clean my injector

There is your problem right there.  Improper cleaning of the upper engine/intake can cause the MAF and IACV to fail or otherwise screw up.

And NEVER go to Walmart or Jiffylube for service/maintenance!