Hey All, new guy here from CT. I have the above truck. I have codes 12 (battery feed to ecm), 34 (speed control servo circut) and 33 (a/c cutout relay). The truck however has no cruise or a/c.

The problem is cold it runs ok, hot it sputters when accelerating and at idle it goes very low idle and wants to stall. Ehaust also smells wierd...I'm stumpped.........

>Bob

 

Well, I put in new plugs, wires, cap, rotor, fuel filter on the frame, seems to runs a whole lot better. i think it fixed the issue. I will know tomorrow when I go to work. But I do have codes 12, no big deal, but code 13 (MAP senson vacuum).......any thoughts.....

 

You either have a vacuum leak or the Map sensor is bad. Have you replaced the 02 sensor in front of the cat? Not sure if it has an Idle air control solenoid or not but if it does clean that if you have not already.

 

Well the issue came back today, moreso when its hot. It's like it stops firing for a second then comes back online then I get a very small "pop", not like a backfire just a pop. I'm replacing the coil with a MSD coil now, see what I get........no I didnt replace the 02 sensor, didnt know it had one, but I'll look. Where is the MAP sensor?

 

Map sensor is usually mounted to the throttle body. Go to rockauto.com and look up the part to see a pic. Around$60. You will have to look at the W100 model truck to see it. Look under the truck at the exhaust pipe before the catalytic converter and you should see the 02 sensor. Around $40 I would replace the 02 sensor first. The Map sensor usually has a small vacuum line from it to the throttle body. The hose may be dry rotted. If the truck is running sluggish it could set the Map sensor off simply because it relies on vacuum from the manifold. Map sensors Rarely go bad. The 02 sensor will make it run rough like a studder or almost stalling. It does not look as if you could clean the Idle Air Control Solenoid as it is sealed unit. You may have to replace that as well. Look at rockauto to see pic.

 

Well,the new MSD ignition coil made no difference, so its not ignition related, everything is new. Under light/moderate acceleration she still pops and cuts off (to where it throws you forward a little because its not pulling anymore........would the MAP sensor do that? I'm thinking fuel pump.........the exhaust seems to smell "off"....not like it usually does.

 

Would either be fuel pump or 02. I would replace both. Is there a fuel rail that feeds the injectors or is it throttle body injected? If it has a rail is there anywhere you can check the fuel pressure like a shrader valve?

 

Its throttle body.......

 

Trace the fuel line to the throttle body and somewhere near there may be a shrader valve you can take the cap off of and check the fuel pressure. you should have a gauge for this but you can get an idea if there is good pressure at idle by pushing in on the valve.

 

Well. today same thing, runs 1/2 way decent cold, when hot, now it barely runs, wont even idle now. Oddly enough, it seems to run on the highway, but in the city, real bad. Progressivlty getting worse. Here are 3 pics of what I think is my 02 sensor, left exhaust manifold. It does NOT have any wire hooked to it, and it never has since I bought the truck 6 years ago..........in bottom pic you can see the bottom of the red MSD coil I just put on......thoughts.....