[JoshCampbell]

I was curious how far I could go on a tank (city driving). Filled it up ($42.00) and ran it until the fuel light +15 miles. I got 162 miles on the odometer. That's about 8 mpg. Slightly better than a Semi. That's pathetic

2001 SE Crew Cab 2WD Auto (non turbo)

 

[JoshCampbell]

I know it's not a fuel leak. My guess is it's a combination of my aggressive driving and shitty 16 year old auto transmission technology. Every time I need to accelerate quickly from a light to get ahead of everyone the truck redlines until I let off the gas, then it shifts into the next gear and just sort of slow crawls until the RPMs get up into the powerband. It's almost as though it needs another gear in between.

I'm a manual transmission guy, so I'm not sure if this is normal or not for older vehicles. I've read that modern autos are comparable to manual due to more gearing, but back in the day (early 2000s) the auto trans were horrible on gas and acceleration. Can anyone confirm this? Should I be driving it like an old lady?

 

[JoshCampbell]

Well I know for sure there's no fuel leaks. I did all the basic tuneup stuff... Plugs, wires, injectors, Air filter, fuel filter, seafoam, converters, MAF, etc. but I imagine there's still work to be done. My dryrotted intake hoses for one. I know the main hose into the manifold has a few large cuts in it. And the entire EGR system has been blocked off. Plus the truck idles around 2k on startup and stays until put in gear and driven for a couple minutes. I guess I'll start there next.

 

[JoshCampbell]

... If nothing else duct tape those hoses/pipes.

I agree with you on the air/fuel mixture being thrown out of whack. I'm also wondering now if it's only idling high on initial start up due to the air temperature. I'm sure I read somewhere that there's a sensor that monitors air temp and factors that in. The smaller hoses are wrapped in electrical tape at the clamp points due to rot and tearing. The main hose is so tightly compressed between the manifold and airbox that I can't hear any air being sucked in through the cracks. Obviously this isn't an ignorant attempt at ruling them out of the equation. Just me fooling myself into believing it's not an emediate priority (been restoring this truck for a while). They're definitely high on the list for this month. And while I'm not overly clueless on the intake system in general I am very much a noob when it comes to the ECU, so all of this is good info. I appreciate it.

I'll contact a few dealerships today for the factory hoses and update on any status changes.

 

[JoshCampbell]

... In some cases this temp sensor is faulty and the car stays in cold start mode.

You may have touched on a game changer there. I thought that the two-wire connector and temp sensor was purely for the temp gauge. My connector broke, so I ghetto-rigged the wires in there to get the gauge working. It's possible the connection isn't good. Though I doubt the temp gauge would work if both wires weren't snug on the leads, but worth a shot to double check when I get home later (drove the 95 Pathy in today... because I like it better lol).

 

[JoshCampbell]

. ..The 2 wire unit is for the ECU. There is another single wire unit that is for the gauge. ...

That's perfect information. The cause and affect seem to align perfectly.

 

[JoshCampbell]

You can get a generic replacement main intake hose off eBay for 15-20 dollars. Courtesy Parts has it for around 50. Mine needs replaced as well. I currently have it wrapped with electrical tape, but I haven't ever had idle problems.

Yeah, definitely need to go aftermarket on these. Dealership wants nearly $300 for everything I need. And I still haven't found the two molded intake hoses that come off the main. Be nice if they just had a ''hoses" section

Oh, and tried manually attaching the temp sensor wires to the leads. No change to the high idle. Also tried jiggling intake hoses looking for idle fluxuation. No changes. Held steady at 2100 RPMs. Thus far putting it in gear is the only thing that drops the RPMs to normal. Still... I'll swap everything out with new parts and repair the wiring before closing the book on them as suspects. Needs to be done anyway, so nothing lost from the cost.

 

[JoshCampbell]

Solved half the problem. Removed the TPS a while back without understanding what it is or what it does. I made sure it engaged the throttle body when I put it back on, but didn't adjust it. The connectors were facing downward as far as it would go.

I simply adjusted it up some until the RPMs were normal, then tightened it back down.

 

[JoshCampbell]

TPS adjustment is critical on these engines and you don't just turn it and lock it down. ...

Sorry, I didn't mean to give the impression that I was going to leave it as is. I went to a pick n pull this afternoon and scored new-ish hoses. After replacing them I noticed no change in the 2000 rpm idle. I also cut some connectors from a decent harness to replace my aged temp sensor connectors. Still no change. I then remembered watching a video on TPS adjustment for the Frontier, in which the guy had his TPS screwed just about dead center. After remembering this I thought 'what the hell' and checked mine. It was way off center, so I turned it to center, the RPMs dropped, and the rest is history.


I intended on following that same video to adjust my TPS tomorrow.