1995 Ford Ranger engine shake, misses

ALEXANDERGRACE

MEMBER
1995 FORD RANGER
3.0L
V6
RWD
AUTOMATIC
132,665 MILES

Okay, bought the truck, ran beautifully. Ac went out two days later, then the odometer stopped working. Car still ran perfect, engine turned over quickly, no misfire/backfire, shifted smoothly, etc. Then I noticed the temp. Gauge would start to run hot, but never overheat, it would just go up and then go down once the radiator went on, asked my dad about it, he said his old ford used to do the same. Radiator wasn't leaking coolant, reservoir stayed full as did the actual radiator. Then I was in an accident, brought it to a buddy of mine he looked it over, checked the frame, no visibe damage besides the bumper, passenger fender, hood and grill. Ac stopped working after we had brought it back to the dealer and he recharged it and ran sealant through it. Few days went by and my car began to occasionally miss on the highway (65-70 mph). Then it began to miss harder and harder as the weeks went on;finally to where I am now. We fixed my exhaust leak, and replaced a cracked vacuum tube that was above the cylinders. Car ran better, didn't miss for a few days. Then it began missing again, and shaking. Rough idle and a diesel engine sound began, kinda of like a chugging noise, sometimes I'd hear a Thumping noise coming from my engine when I turn it off. Replaced wires and plugs, still did nothing. No check engine light, but we decided to check the codes and I got one that was pertaining to EGR, anoher about the Camshaft sensor and syncronizer and one that said my system is running to lean. When I asked my uncle ( a ford mechanic for 25 years) he said I have a vacuum leak. We checked the connector to the cam sensor and it appeared to be practically crushed. Now, I have received money from my insurance to fix the car, but I don't want to fix the cosmetic problems and have the engine die, leaving me with practically no money to fix it. Insurance said if I can get my problems diagnosed and get them classified as accident related theyd pay for the repairs, but I have no idea what to tell a mechanic if I were to bring it to a shop to get looked at. What should I do?

Tuesday, October 14th, 2014 AT 11:15 AM

1 Reply

CARADIODOC

MECHANIC
34,330 POSTS

You described the problem perfectly. Do that in words, or show your mechanic this post.

The only thing I can add is about the temperature gauge. A lot of people don't even pay attention to it until it's too late. The coolant temperature sensor for the dash gauge is a little ways away from the thermostat. As the engine warms up, the heat in the coolant has to migrate over to the thermostat to cause it to open and let coolant flow through it. By the time that happens, that higher temperature has already been detected by the sensor so the gauge reads a higher temperature. Once the thermostat opens, cold coolant in the radiator rushes into the engine and up to the sensor and thermostat. In response, the dash gauge goes down and the thermostat closes. The whole process repeats again. That suddenly started happening after about 15 years on my '88 Grand Caravan after nothing was done to it. The gauge would go up and down wildly four or five times before it would settle down.

The fix for that is to drill a tiny 1/16" hole in the plate in the thermostat, then reinstall it. That will allow a little trickle of coolant to flow all the time so the hotter coolant can reach the thermostat sooner. That hole is way too small to affect the operation of the thermostat in any other way. Most import engines have the same problem and you'll find their thermostats already have that hole and a little "dingle dangle" hanging from it.

As for the misfire, the spark plugs and wires are the most likely suspects, but don't overlook the ignition coil. Ford has plenty of problems with them. If they start to arc internally, that can happen when just one cylinder is firing if that spark plug needs more voltage than the coil can deliver before it arcs internally instead. (Electricity takes the path of least resistance). The symptoms should change when the new spark plugs are installed because the new plugs will take more or less voltage than the old ones just because their gaps are different.

Ford also has a real common problem with their EGR systems on their full-size trucks. I don't know if this can happen on a Ranger. The tube carrying the exhaust gas to one cylinder gets plugged with carbon so that cylinder only gets fresh air and gas, and it works fine. All the exhaust gas is split among the remaining cylinders, five in this case, assuming, again, this applies to your truck. Those five cylinders still get enough fresh air and gas to run okay. Pretty soon a second tube gets plugged, then a third one. The volume of exhaust gas is what's controlled, and the engineers just assumed it would be split evenly among all the cylinders. Eventually all but one tube is plugged, and since the overall EGR volume is staying constant, it all goes into that one cylinder. To say it a different way, that one cylinder gets six times as much exhaust gas as it's supposed to. That is the only cylinder that is working right, but it's the one that will misfire because all it has is spent exhaust. It doesn't get any fresh air to go with the fuel.

There are a lot of fault codes related to the EGR system and they mean different things. If your code refers to volume or "insufficient flow", check for carbon plugging the tubes.

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Tuesday, October 14th, 2014 AT 10:27 PM