I'll try cleaning the TPS tonight and check the vacuum lines.

You right, the truck does need a good tune up, I bought it used and I think it has around 129,000 miles on it.
It needs some other work too but my main concern is getting the darn check engine light off so I can get it inspected.

What would you do if you were me? and tight on cash at the moment.
Start with the O2 sensor? (about $65)
Start with plugs,cap,rotor,wires? (about $60)
Clean & check the TPS. (new one is about $50 )
or start with the vacuum lines?
or anything else??

My main concern is the backfireing and lack of power. It always seems to happen at the worst moment, like when I'm pulling out in front of someone or at a traffic light. Or driveing by some females, then bucking and backfireing right when I'm beside them.

It does idle rough when stopped, but if I put it in neutral, it idles fine, then when I put it back in drive it seems fine until the next backfire.

 

have you actually checked anything in the engine?
my cousins jeep was shaking and doin all kinds of weird stuff, like not goin above 2500rpm all it ended up being was a bad distributor cap and rotor, check small stuff like that before spending so much on a mechanic, its not like its gonna hurt

just take the distrib cap off and look at the rotor should just be held on by two philips head screws

 

Thanks Josh.
I'll check it out tonight. As much as I can. I dont want to bring it to a mechanic if I dont have too.


This might be a dumb question but how would you know if the dis.cap is bad or not? Am I looking for cracks or bad/dirty contacts? How do you know if the rotor is bad? Will it be black or discolored?

 

when you take the cap off the inside of that will have little electrodes sticking down if they looked jacked up needs replaced, which most likely means the rotor is bad
the rotor is the little piece that spins around in the cap and should look kinda shiny, if its dark replace it, they are cheap should be less that 20 usd for both ill check to see if we've still got the bad rotor from the jeep and post a pic for ya

edit: ahh nope we chucked it

 

Well if you are short on cash, you can check the lines and hoses on the emissions evap system yourself. Smack the cat with your hand to check it out, if it rattles like it's got gravel in it it is bad. Either get a cheap volt meter at Harbor Freight (they sell one that is only $2.99 when you can find it on sale) or borrow one and check your TPS output voltage. You can clean the IAC for free if you have some carb cleaner on hand too.

You can get by with a cheaper distributor cap and rotor, can probably get both at Autozone for maybe $12.00. You could even get the cheaper spark plug wires for maybe $20.00 but the cheaper parts don't last as long. They would work though, for the time being. You can also get 3923's at Walmart pretty cheap. Last time I checked they were about $2.80 for 2 plugs in a pack. You could even just replace the plugs and use the original plug wires, as long as they don't break when you remove them. I have heard of guys using the same wire set for 150 and 200,000 miles. I just don't do that myself. I replace mine at every 40,000 miles. If the rotor button end is blackened or looks grayish/white it needs to be replaced, just like Josh said. Same for the electrode connectors inside the cap.

You may not need a new TPS sensor, but you need to check the output voltage to be sure. You probably do need a new O2 sensor, since you have the code for it. You can start with the cap, rotor and plugs but since the O2 is bad, the truck probably will still have problems until you replace the O2. At that mileage if it has never been replaced, it is most likley shot.

Jimmy

 

Thank you very much guys.
I will try some things tonight and let you know how it went tomorrow.

 

First, replace the ignition components and correct the misfire code and clear the computer. The rest of the problems might go away.
An Oxygen sensor is just that- it picks up on oxygen in the exhaust system (should not be any) If there is, then there is unburned gas escaping from the engine. It is basically a 1 volt battery that is oxygen-activated. When it sniffs oxygen, it creates 1 volt (+ or -) and that is what lights up the check engine light.

At least that's the way it was explained to me when they first appeared on the scene many years ago.

 

I checked the manual tonight and bank 2 is the right side (passenger's side) exhaust, and sensor 1 is the Oxygen sensor before the cat-the upstream sensor. Bank 1 is the left side (driver's side) and sensor 1 is the upstream sensor on that side. The downstream sensors (after the cats) are called the #2 sensors.

Hope that helps.

Jimmy

 

does anyone now what the spark plug gap should be for a 91 dodge van b250 v8 with 318

 

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