Question:   2003 Ford Mustang mileage 71,000. Service Engine light on. Car runs rough between 35-40 Miles per hour. “Lopes.” Code reader says EGR Flow Low. Replaced EGR vacuum regulator and EGR valve with no luck. Lots of black smoke in exhaust. Service engine light used to be intermittent but now it's always on. Ford did warranty work on this car at about 20k miles, and removed the intake manifold, and removed "fouling" from the interior of the manifold. Any suggestions?

Answer: Your problem sounds like a EGR (exhaust gas recirculation) valve is failing. Remove to replace with new to recheck system.

Question: 1996 Ford Ranger mileage 133,000. Truck starts and idles well. However when it gets warmed up (probably 20 minute drive) bucks jumps lurches almost acts like it is shutting off and on. This started happening after I had tune up (in July ran very well until Nov.) new dist, wires, plugs, coil, fuel injectors cleaned. Started just an occasional jerk then got so you did not dare drive it far. One garage said needs new throttle control valve, installed did not fix, next time EGR valve and PVC valve, installed still no fix. Next time they retarded timing ran well for maybe 2 weeks, no power but didn’t jerk. Now they are suggesting idle control motor? Another said the fuel pump. Any suggestions before I donate it to charity? I don't mind spending the money to fix it but when it doesn’t fix it I get frustrated. Should I take it to a Ford garage? Please help!! I love my old truck and hate seeing it like this!

Answer:  The fuel pump sounds like it is failing, check fuel pressure it should be between 45 - 55 psi. If not replace fuel pump with new to recheck system.

Question: 1999 Jeep Cherokee Mileage: 101,000. The trouble I am having is the engine is not running on all 6 cylinders. Check Engine light is on and giving me a code "P027" which is a problem in the injector control circuit. The throttle position sensor was replaced, and I even used a known good ECU (electronic control unit) out of another Cherokee just incase the ECU was bad; engine ran fine for about a minute before the Check Engine light came on with the same code "P027." I even used Noid lights to make sure the ECU was firing the injectors. All checked out okay there. Finally, a repair shop told me the computer and wire harness appears good. Any new avenues to explore would be greatly appreciated.

Answer:   It sounds like you have an injector that has failed and need replacing. Test across the injector terminals to test resistance 20 Ohms to 30 Ohms. Replace shorted injectors as needed.

Question: 2002 Chevrolet S10 Blazer, miles: 78,900 The problem is that the engine is so rich at idle that it lopes and stumbles. I replaced plugs (AC), wires (GM), coils and fuel filter and performed all the basic checks before I took it in for diagnostics. The dealer said that the fuel injector was bad. I did not believe them so I took it to someone else; they told me the same thing. I replace the injector ($$$) this had no effect on the problem. It is not logging any trouble codes in the computer. I have now performed a compression test and all the cylinders are fairly even between 158 & 170. I also took the valve covers off and measured the lift at the rocker arms to see if there might be a cam lobe going down nothing out of the ordinary there. I checked the fuel pressure it has 62 lbs at start and 54 lbs running. I have swapped the crank position and the cam position sensors off my s-15, the idle air control and have also swapped the O2 sensors. I have checked anti-knock sensors 8400 ohms, I have tested the throttle position sensor and the engine coolant sensor all of which checkout with the book that I have. It has 17 inches of vacuum at idle so I don't think that it has a leak. Also the timing seems high 22 degrees BTC. Nothing that I have done so far has any effect on the problem. Any ideas?

Answer: We suspect a faulty fuel pressure regulator is causing your problem. The regulator may have a ruptured diaphragm allowing the raw fuel to leak into the intake manifold. Disassemble to replace as needed, reassemble to recheck system.

Question: 1999 Chevrolet 1500 4x4 mileage: 125,000. I have taken my truck to 3 different mechanics and no one can figure out the problem - I have had my computer replaced but that didn't change anything. It runs as though there is a miss but have had a tune up and that didn't change anything. The computer didn't read anything wrong which is why they replaced computer. Do you have any idea what it could be? It runs fine when cold as soon as it heats up it runs terrible.

Answer: Your problem may be low compression in a cylinder causing the miss fire. Test as needed to determine the cylinder, disassemble to repair as needed.

Question:   2002 Honda Accord mileage: 68,500. My Accord started running bad, I did a leak down test on it to find no compression in the #1 cylinder. I've taken the head off to find a burnt exhaust valve. Should I have the head sent out to have it magnifluxed or am I ok to go back together just lapping the valve in. The head looks good, no other burnt valves, really clean. I appreciate your time in this matter.

Answer:   In your situation, we grind all the valves and valve seats. We check the valve guides for wear and replace all the valve stem seals and the head resurfaced. If your engine has been overheated or if you are concerned, have the head pressure tested for cracks.

Question: 2001 Ford Explorer mileage: 95,000. I seem to have a problem related to moisture, but can't pin it down and the local dealer has been of no help. When driving my Explorer when the roads are wet or snowy, occasionally the engine will "buck" or hesitate for just a split second. The frequency may vary from once every minute to only very occasionally and usually at speeds from 40 and up. I've looked at plug wiring, exposed cabling, etc and can't find a thing. No code shows up when hooked up at the dealers, but then again, it doesn't do it when sitting at idle. Any ideas?

Answer: Your car is ready for a tune up including spark plugs, spark plug wires, fuel filter and air filter. Replace as needed to repair problem.

Question: 1998 Nissan Pathfinder mileage: 120,000. Put a new engine in.  When it idles, it runs beautiful but drive it out on the road up a small grade and it misses and cuts off. Took it to electrical tech. He made all tests, fuel pressure at 43 psi, vacuum, alt, fuel getting to fuel injectors. Nothing. They were stumped. I even put the problem online to other mechanics and got no answers. We changed computers, got used coils and switched them when it tested it. The only thing it said was it might be an open circuit in the ignition side. Any idea's would be helpful.

Answer:   It does sound like you have a ignition module that is beginning to fail.  Replace with new to recheck system.

Question: 1999 GMC Sierra 1500 mileage: 145,000. Other than plugs and plug wires which are all firing properly, what would cause the diagnostic readout to come back as misfire on cylinder 8? The vehicle runs very sluggish almost like vacuum leak or dirty fuel filter, which have all been tested negative. Your answer would greatly be appreciated I am running out of -------. THANKS

Answer:   Sounds like you may have a failed fuel injector for number 8 cylinder. Replace with new to recheck system.

Question:   2004 Dodge Dakota mileage: 80,000. Engine running rough - mechanic at dealer says probably dirty gas filter. Asked were it is. They told me they would have to remove gas tank. Its inside. Cost: $120 for a gas filter seems quite STEEP! Could you let me know what you think?

Answer:   We do not think the partially plugged fuel filter would cause your car to run rough. If you have not recently had a tune-up, you may be ready for one. Including spark plugs, spark plug wires, fuel filter and air filter. Replace as needed to repair problem.

Question: 1995 Chevrolet 1500 pickup mileage: 130,000. The truck has throttle body injection and no trouble codes. Has new computer. Can remove wire and set timing, reattach wire and it will advance properly. Turn off engine and restart and it spits and sputters as if it has lost its memory. Runs better with the Prom removed, yes it has been changed too.

Answer:   Check the ground connections for the ECM. If this checks okay, try changing the ECM. Also check fuel pressure (14 - 20 psi.) you might have a problem there.

Question: 1999 Ford F-150 4x4 mileage: 141,250. My truck starts hard when cold (6 to 8 turns. Once started, it runs well for about 2 to 3 miles until the EGR valve kicks in. Then the engine stumbles/skips for about 2 miles. However, when the engine does warm up and the temperature gauge is in the normal position, everything is fine. I have replaced the EGR valve, but it has not improved the situation. I have talked to several mechanics that have said that it is engine design flaw concerning the fuel distribution to the fuel injectors. The fuel doesn't get to all cylinders in time when the engine is cold. Have you heard about this? Do you have any suggestions or do you know of any aftermarket fuel system changes that you could recommend to avoid this problem. I am running out of ideas and Ford doesn't seem to have answer to fix the situation. Thanks for your time and help.

Answer:   This is a difficult problem to detect because the computer can not sense a malfunction, the vehicles computer system thinks everything is ok. In reality what is happening is the electrical component inside the MAF sensor becomes contaminated by air impurities. These containments imbed themselves to the electrical component that senses the air flow causing the sensor to be slightly off, but not enough to trigger the MIL (malfunction indicator lamp). Replace the MAF sensor with a new. NOTE: (Mass Air Flow MAF sensor or Air Intake Sensor AIS, depending on manufacturer. It does the same thing only with different names).

Question: 1999 Ford F150 mileage: 125,000.  Two different mechanics cannot solve our problem. Our truck starts fine, and then on cue, after approx. 10 min running time, it begins to stall and buck.  The check engine light comes on and the rough running continues for the duration of the trip.  The code that is set points to a faulty oxygen sensor.  We've replaced it twice.  Once with an after market sensor, then, on the advice of the second mechanic, a genuine ford sensor.  No change. We've replaced the plugs.  We've checked the fuel pump pressure, replaced the in-line fuel filter, nothing so far has fixed the problem.  This is frustrating since the truck is in excellent condition.  We are at the point of replacing the "so called" computer on the truck.  However, I'm not optimistic that the problem lies there.  Again, the symptom: truck starts fine, but after warming up, begins to miss and buck.  It's possible to accelerate and drive out of the problem, but it returns almost immediately.  It's really bad in stop and go traffic, it cuts out badly in 1st gear, esp. on inclines.  We've been struggling with this problem for over a year, any help would be greatly appreciated.  Thank you.

Answer: Check the fuel pump relay, the ECC relay, the fuel pump pressure when the problem is occurring – you may have a faulty fuel pump.  There is also a chance you may have a faulty engine computer.

Question: 1999 Ford F150 mileage: 126,643.  Check engine light on-running rough-diagnostic check says misfire on no. 2 cylinder steps taken are: spark plug wire changed-engine compression test done, it was ok-no. 2 fuel injector changed-checked for vacuum leak-ok-new spark plugs and wires w/tune-up what else could it be?

Answer: Check for a shorted ignition coil, replace with new to recheck system.

Question: 2001 Pontiac Grand Am mileage: 93,578.  My Pontiac Grand Am with a 2.3 liter Quad 4 engine is running ruff. It is missing and won't idle.   When checked the #1 & #2 cylinders don't make any difference in the motors idling when the fuel injectors were disconnected only cylinders #3 & #4 make a difference.  The injectors are functioning.  The plugs show signs of weak spark the other cylinders are fine.  Compression tests show all cylinders good.  The coils have been checked.  The ignition module replaced.  What could the problem be?

Answer: Check the ignition coil housing, sometime when coil housing short circuits they can cause a cutting out effect. Replace ignition coil housing with new to recheck system.

Question:  1999 Ford Crown Victoria mileage: 80,000.   I have a problem when I start the car it runs rough it is like if the timing is off.  I replaced spark plugs, cleaned throttle body and idler air sensor, replaced EGR valve, ran vacuum test seems no leaks, tested fuel injectors all fine.  Checked engine compression and its ok.  Checked valve springs ok and timing chain seems to be tight.  I was hoping you could help me.

Answer: It sounds like you have a ignition coil that has failed, remove to replace with new to repair problem.

Question: 1999 Dodge Caravan mileage: 102,245  We have problem with engine when it is cold out side it runs great.  But when weather warms up the car when driving on highway will act like it runs out of gas and coast a little ways.  Then it will start up on its own and run fine for miles or hours.  Have installed new and filters.  Dodge dealer in Scottsbluff said they could not find the problem.  If you have any ideals or question.  Please write back.  We are lost.   Thank you for your time.

Answer: Try changing the fuel pump, the pump motor can start and stop at will when it is ready to go out completely. Replace fuel pump with new to recheck system.

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