Sir_Brando Posted February 12, 2011 Share Posted February 12, 2011 Halfway through my day last Wed my comanche started doing this. The best way i can describe it is the truck was limping while trying to drive. Ill try to explain the best i can. Once i got around 10mph in first gear it started lurching pretty bad and accelerating only made it worse. Shifting into second made it putt putt and limp along. Stomping the gas only made it putt putt faster, like a spattering at high rpms. Finally once it got between 15-20mph, i shifted to 3rd to see what it would do. It did the normal bog down during low speed in a high gear. It was extremely nasty out so i convince myself to limp it home and figure it out there instead of checking it out and being stranded out in cold and snow. Thank god for the manual trans, don't think i could have got it home without it. My muffler is extremely rusted out with a big hole in the side of it.(very next thing on the list of things to replace) So my initial reaction was the exhaust had finally had enough but i really have no clue. After searching across multiple forums, those symptoms seemed to match what i had goin on the the general answer was the exhaust. One answer i ran across talked about a spring loaded connection at the exhaust manifold to pipe connection that lowers the pressure in the exhaust system so one can limp the car home or to a repair shop. I took a handful of snow and held it on the cat. it hissed and evaporated pretty quickly. Same with the pipe going towards the muffler. The snow melted a little when touched to the muffler but didnt his and evaporate. I didnt even bother with the tail pipe. like i said, my muffler has a huge hole in it and thats where the exhaust dumps anyways. The end of the tail pipe is usually cold to the touch. Sorry for the novel, I'm just looking to confirm the exhaust is my problem or if i need to be checking other things. I would just replace the exhaust but if its something completely different id rather get it drivable before buying a new muffler. My idea today was to unbolt the cat from the dp but i just rounded the extremely rusted bolts off. Gonna go shoppin with the fam after the post and chisel the bolts off when i get back. If i can get the cat back off and drive it around then thats enough convincing for me to go ahead and replace it. I'm attaching a video to show what point not to let your muffler get to. And two other videos with possibly another issue, related or not, a sound from the intake when i shut off the truck i have no idea about. Thanks for any help fellas. Intake - b2Gs-cM2jJI IDLLPbeHFAc Link to comment Share on other sites More sharing options...
jas2861 Posted February 12, 2011 Share Posted February 12, 2011 Could be a couple of things.... Does it have a cat. converter.... if so, its probably plugged. Also it could be your coil, plugs or wires. Search to test the coil, and wires on this site. I would check the cat. converter though first!!! Link to comment Share on other sites More sharing options...
Vintage Posted February 12, 2011 Share Posted February 12, 2011 From the symptoms you described, I would think fuel filter or possibly the cat. Link to comment Share on other sites More sharing options...
JeffN Posted February 12, 2011 Share Posted February 12, 2011 if the cat was plugged it would probably be glowing red. check vacuum lines to your map sensor and well, change the fuel filter anyways it is always a good idea to change that. Link to comment Share on other sites More sharing options...
Sir_Brando Posted February 13, 2011 Author Share Posted February 13, 2011 Ive already been having some vacuum issues so I'm picking up some more hose in the morning and finishing gettin rid of the brittle stuff. Ill check the connection to the map while i do that. I'll pick up a fuel filter, plugs, wires, etc as well. I haven't changed those in a while. Ill look tomorrow but as far as the cat goes, without looking at it, i think its alright. Seems to be just as hot on one side as the other. I'm gonna chisel through the bolts in the am and check it. Forgot to mention this, but it idles fairly well. Doesnt sound like a plug or wire. However, a couple times, after idling fine for about 10min it just sputtered out and died. Ive also been working on an extremely high idle. I wasnt gonna ask for help with it until i bought a tach so i could give some numbers. I'm gonna dig into it in the morning and hopefully answer some of my own questions. Thanks for the suggestions. Link to comment Share on other sites More sharing options...
Sir_Brando Posted February 16, 2011 Author Share Posted February 16, 2011 I changed the fuel filter, plugs, and wires. I couldn't get the exhaust off before the cat, so I opened up the muffler at the hole and cleared out the insides. I'm getting a normal amount of exhaust coming out now, so I don't think that's the problem anymore. It's running smoother now, but the rpms are wavering really bad now. I haven't let it warm up yet or try to drive it. Without the muffler, I'd rather wait until tomorrow instead of waking everyone up. For the MAP sensor.. With the key in on and the engine off, the multimeter reads 5v at the middle contact(B). At idle and not completely warm, it reads about 3v. Is there more than that to testing the sensor? If not it looks good to me. Is there something with the carb i could be doing? Clean up under the valve cover? Test the fuel pump? An electrical problem? I'll fire it up tomorrow and let it chug for a while to see how it acts. Link to comment Share on other sites More sharing options...
cz777 Posted February 17, 2011 Share Posted February 17, 2011 if the cat was plugged it would probably be glowing red. check vacuum lines to your map sensor and well, change the fuel filter anyways it is always a good idea to change that. a cat can snowball closed some/all flow ! look over all above !! Link to comment Share on other sites More sharing options...
fiatslug87 Posted February 17, 2011 Share Posted February 17, 2011 Have you checked the EGR system? My '90 4.0 had similar problems that were resolved when I changed the EGR valve. Not sure if the 2.5L has an EGR. Link to comment Share on other sites More sharing options...
kyleag89 Posted February 17, 2011 Share Posted February 17, 2011 You should cut the exhaust off right after the cat and look inside. You have to replace the muffler anyways and you will need to cut it off there. If it looks like a honey comb then it should be good to go. Link to comment Share on other sites More sharing options...
airspeed Posted February 17, 2011 Share Posted February 17, 2011 I had a similar problem on my 2.5 and found a couple of plug wires were shorted together and cross firing the cylinders. The harder you push the gas the worse the problem got, I barely got home in second gear. Move the plug wires so they are not touching each other to see if that makes a difference. Or with your engine running open your hood in the dark and take a spray bottle with water and spray the plug wires, you will see a light show. Link to comment Share on other sites More sharing options...
Sir_Brando Posted February 19, 2011 Author Share Posted February 19, 2011 The EGR was completely clogged. I cleaned that baby out and its moving freely and working. I tested the TPS, the input ranged from 1v closed throttle to 5v open. The output read 5.07v regardless of what position the throttle was in. Adjusting the TPS didnt change the output reading at all so i fine tuned the input reading. does this mean the tps needs to be replaced? Current symptoms: Starts fine, attempts to idle fine, then RPMs drop significantly. opening the throttle, it does the same thing. idles very high(foot on the gas) then rpms die down to the point of killing the engine if i don't stomp the gas. Its a constant wavering up and down in RPMs. It makes it impossible to drive. I still have a laundry list of stuff to check. hopefully someone can add to the list and give me more to check Already changed the plugs and wires and its just wavering smoother now. doesnt seem to be the problem. Link to comment Share on other sites More sharing options...
Sir_Brando Posted February 23, 2011 Author Share Posted February 23, 2011 BUMP I tested the TPS, the input ranged from 1v closed throttle to 5v open. The output read 5.07v regardless of what position the throttle was in. Adjusting the TPS didnt change the output reading at all so i fine tuned the input reading. does this mean the tps needs to be replaced? I took the TB off and cleaned it all up. Should I/can i do anything with the piece in the middle of the TB? Thats the injector i presume?? I cleaned the dealy with the spring and rubber thingy in it next to the TPS. Anything else while the TB is off the manifold? I'm going to rent a pressure tester from autozone to check the fuel pump. Link to comment Share on other sites More sharing options...
Sir_Brando Posted February 27, 2011 Author Share Posted February 27, 2011 After everything I've cleaned/replaced, it runs relatively better, but I'm still having problems. I'm not sure what the right term is. Loping? Erratic idle? I think I've narrowed it down to the fuel pump. Here's a video of the test I did. z4pEHT2Ka38 Gauge stays at a steady 6(approx) while running. Link to comment Share on other sites More sharing options...
comanche12 Posted February 27, 2011 Share Posted February 27, 2011 look like fuel regulator is bad since it won't closed the valve to help pressure build up. try check regulator before check pump. I'm not expert on fuel system though :dunno: Link to comment Share on other sites More sharing options...
cz777 Posted March 1, 2011 Share Posted March 1, 2011 that is a plug facing the driver's side fender on the TBI unit -look at both fuel lines on back now to the plug the fuel psi is around 14 pounds .. Link to comment Share on other sites More sharing options...
Sir_Brando Posted March 1, 2011 Author Share Posted March 1, 2011 Problem is fixed. I grabbed a new fuel pump and that solved the problem. look like fuel regulator is bad since it won't closed the valve to help pressure build up. try check regulator before check pump.I'm not expert on fuel system though :dunno: I completely cleaned every part of the FB/TB including the regulator which it seems like it should be adjustable? Mine was not. that is a plug facing the driver's side fender on the TBI unit -look at both fuel lines on back now to the plug the fuel psi is around 14 pounds .. No idea what you're getting at. I don't have the fuel pressure tester port that goes into the fuel body. The rental kit from autozone didnt have any attachments for the FB either so i used an in-line port just forward of the filter. You can see in the video that i already had a gauge hooked up and it was reading around 5-6. All together this is the work that was done before fixing the problem with a new pump: 1. removed muffler 2. new plugs/wires 3. replaced all vacuum lines and the hideous vac tree with rubber vacuum hose(approx 10ft) 4. EGR was completely clogged w/carbon - cleaned and checked good 5. found vacuum hoses hooked up incorrectly 6. new fuel filter 7. completely took apart fuel body/throttle body. soaked and scrubbed 8. MAP test, MAT test x2 9. TPS adjustment 10. new fuel pump/strainer A week and a half, 1 case of beer, and half case of redbull later, she's purrin. This baby hasnt run this good since ive got it. Link to comment Share on other sites More sharing options...
comanche12 Posted March 1, 2011 Share Posted March 1, 2011 Ah now you got it solved, :cheers: Same with me that I haven't have her purrin when bought her and fixed her up. I'm sure you feel alot better! :thumbsup: Link to comment Share on other sites More sharing options...
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