Question: 2004 Ford E-150 Club Wagon mileage: 78,000. Van has an intermittent miss while accelerating. Van has had a recent complete tune-up, complete with new oxygen sensor. Has been to Ford garage 4 times and checked on their analyzer with EGR problem. EGR valve and positioning sensor has been replaced twice with no results. Ford cannot seem to get it fixed. They say it is internal carbon buildup and would have to go into the top end of the engine to correct, very difficult in the tight space on top of engine in a van. I have run several cans of fuel system cleaner thru the gas but has not helped. Ford said they disabled the EGR system and the van ran fine. But, of course, they cannot leave it disabled. Is there a way to dissolve or remove carbon buildup without actually going into the inside of the engine?

Answer:   This is difficult because the computer can't detect a problem, your van thinks everything is ok. In reality what is happening is the electrical component inside the MAF sensor becomes contaminated by the impurities in the air (heavies) These containments imbed themselves to 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 sensor and you're problem will go away, plus your car get better mileage and performance. (Mass Air Flow MAF sensor or Air Intake Sensor AIS, depending on manufacture. It does the same thing with different names).

Question:  2004 Chevrolet Impala mileage: 84,000. Engine began to miss shortly after I ran out of gas one day.  Now, engine misses mostly when cold while lightly accelerating.  Seems to miss only when the throttle is slightly applied and held steady.  When at cruising speed, it will also miss at times.  It never misses at idle or when under medium to heavy acceleration.  Dealer couldn't find problem, but did an ERG cleaning of the system.  A fuel filter has been replaced, sparkplugs and wires have been replaced.   

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:  2002 Chevrolet Corvette mileage: 75,000. What typically causes a trouble code  I've replaced the oxygen sensor twice; the catalytic converter has been replaced. Could you point me in the direction of what components would be faulty since I have replaced many? Thanks in advance.

Answer:  It sounds like your car is ready for a Mass Air Flow sensor. Replace with new to repair problem.

Question:  2001 Honda Accord mileage: 74,500. I just changed my plugs and wires and I did it one by one (took off one wire then the plug, put new plug back in then the new wire) and I’m positive that it is in the right order and I started it after I got done and it would idle and rev up fine but when I took it out for a ride and got on the gas it started miss-firing so I got out to make sure that nothing was loose and everything was fine. It baffled me so I ask a few other people and they didn’t know, can you help?

Answer: This can happen when inferior replacement parts have been installed. OEM auto parts are the professional choice just for problems like this.

Question:   2002 Dodge 1500 Ram Truck, mileage 59,000: My truck has been bucking and jerking a lot lately. It's a 5 speed. Bucks and jerks as you gain rpms in each gear. It usually starts at around 1800-2200 rpms, but varies. I have had the service engine light come on a few times...it goes out after a while. I took it to the garage and they said it was a fuel pressure regulator leaking and replaced it at $382...it is still bucking and jerking. They then said it had plugged injectors... cleaned twice and still jerking. They said the codes said cylinders 1, 3, 6 were misfiring. They said bad gas...dropped tank and cleaned but then they said it wasn't the gas after all as the tank was clean. They replaced the fuel pump after breaking the sending unit on it and replaced the fuel filter. It is still bucking and jerking...service engine light on again. They said codes say cylinders 1,3,4,6 are misfiring now....needs injectors in all 4 cylinders. Would this be correct as it sometimes seems to run GREAT...other times it bucks and jerks. I'm at a loss as the garage “seems” to be guessing now and it is getting costly for a “no fix” so far...$643 for the 4 injectors replaced if it needs it as they say it does. Any suggestions?

Answer:   It sound like you need a major tune up including spark plugs, spark plug wires, fuel filter and air filter. Replace as needed to repair problem.

Question: 1987 Chevrolet Corvette mileage 70,000. My Corvette just died at a stop light recently; it was very hard to restart and ran very poorly. After starting, it sounded like it was running on 3 cylinders and died out again. Towed it home and pulled a couple spark plugs which were ok. Tried to start the car again and it ran fine for about 15 seconds and then ran real rough and died again. Then I checked for engine codes and it came up with no code. I replaced both the power and burnoff relays along with the mass air flow sensor because it was the original. Also changed the spark plugs. Went to start the car and STILL have the same problem, sounds like it's idling on 3 cylinders and dies out. I also noticed when the car was idling very rough that the right side catalytic converter looked red as if it was very hot. Any ideas what's wrong?

Answer:   Try replacing the fuel pump. If the fuel pump malfunctions it can cause the engine to run rough and misfire. Replace fuel pump with new to recheck system.

Question: 2003 Mazda MPV Van Mileage: 82,000. The car is running really rich, especially when I start it in the morning. When the car is warm, it seems to run fine, well most of the time. Parts I have replaced recently are the O2 sensor, timing belt, distributor cap, spark plug wires/plugs, and air filter. I am currently getting about 12 miles to the gallon.

Answer:  We suspect that the fuel pressure regulator has failed and needs replacing.

Question: 2002 Honda Accord, Mileage: 83,000. Being adventurous and persistent, I decided to replace my own timing belt...I just finished today. I was very careful to line up all the marks, and I was ecstatic when the car actually started after I put everything back together. But I have a check engine light that is on that doesn't remove itself with the simple negative battery cable removal trick, and the car runs great...until the motor speed gets to 3000 rpm where it bounces in a range of 2750 to 3250 rpm, independent of how much gas I apply. I have taken the valve cover gasket off to check the marks on the cam to make sure that they line up with the crank...and they both look perfect. I'm pretty sure the balance shafts are correct as well...I was very careful. Could I have damaged something to cause this problem? Is the car so old that "correct/factory timing" is off and I should adjust for that? Please help if you can...btw, this car doesn't have adjustable spark timing, as far as I know.

Answer:   Look at the air intake senor to make sure it is connected. This is the one item that causes a check engine light on reassembly.

Question: 2000 Infinity G35 3.5 Coupe, miles: 45,980. Hey I really love your site. This has stumped other mechanics. You're my only hope. The car usually idles fine, but when you put it in gear and step on the gas it sounds like it backfires in the engine up by the air filters? This happens on Initial acceleration but gets better like on the freeway. I took it to a mechanic who changed the TPS again and said it was fine now. Months later the same thing happened, it came back. Went to another mechanic and did it all over again. What could it be? Could it be the actual computer that's fried? If I go to another mechanic, how do I know they know what they are doing because they seem to know about as much as I do with this problem? I love my car. Please any suggestions or insights would be great.

Answer: Replace the MAF sensor with a new sensor and you're problem will go away, plus your car get better mileage and performance. (Mass Air Flow MAF sensor or Air Intake Sensor AIS, depending on manufacture. It does the same thing with different names).

Question:   1993 Dodge 3500 Ram mileage: 102,000. My son's truck drives poorly and is driving me nuts. The truck chugs as if rich and has low power and poor mileage. The EGR appears to work correctly. I can see the pintle move as the engine is revved. Adding vacuum at idle kills the engine. Oxygen sensor replaced 3 times! Still getting "too rich / too lean" codes. TPS, Map, CTS, all pass tests or have been replaced. Where to go now?

Answer:  Check for a failing fuel pump, check fuel pressure it should be between 55 - 65 psi. If not replace fuel pump with new to recheck system.

Question: 2003 Chevrolet Express 1500 mileage: 81,000. I swear my van is haunted. This isn't the first incident, but it's the most recent. Perhaps you have a clue as to what's going on. Monday morning, the "service engine soon" light comes on, within 15 seconds of starting the van. At first, there's no noticeable degradation in performance. After it warms up, it seems to be running a bit rough. Also seems to be getting just a bit warmer than normal. Drove it to work this way, but decided when I got there to take it to a shop. I took it to a local shop near where I work. Their computer scanner indicated that the car needed an oxygen sensor and an ignition module. Not knowing what an ignition module was, I remarked that the van started and ran, so I couldn't understand how an ignition module would be the problem. I asked them to replace the O2 sensor and change the oil. When they were done, the car behaved exactly the same - the "service engine soon" light still came on, and it still ran rough. Not wanting to be further taken advantage of at that shop, I took the car to a different shop near where I live, the next day (perhaps that was my biggest mistake). They confirmed that the codes indicated that an ignition module was required.

 After asking them to make sure it wasn't something simple like a spark plug wire, and after waiting an entire day for them to look at the spark plug wires, I told them to replace the module. They did, and the car STILL did the same thing: service engine soon light is on, runs rough, and the computer codes STILL indicate it needed an ignition module. I had them reinstall the original module and RAN away from their store as fast as I could. I should have known better than to take the car to the same shop anyway, but I never imagined it would really be a tough nut to crack. So, my question is, have you guys ever heard of a similar situation? That is, a computer indicates two parts need replacing, you replace them, and the problem still exists. The code for the ignition module still returns even after being cleared multiple times (and the battery being unplugged). The service engine soon light still comes on, and it still runs rough. Spookier still, the light doesn't always stay on. This evening after work, my wife took the car on a couple errands. After she returned, I took the car out. The 'service engine soon' light DID NOT COME ON for a while. I only drove the car 3 or 4 miles, and just as I pulled up into my driveway, the light came on again. Also, while it was not lit, the car wasn't running rough any more... it seemed to run normally. Spooky, no? Any ideas?

Answer: It sounds like your fuel pump is starting to fail and needs to the replaced to repair problem. Replace with new to recheck system.

Question: 1993 Pontiac Sunfire, miles: 89,900. Car starts fine, drives fine for a few minutes in the morning, however after a while any load on the engine causes it to jerk violently (I bit right through my tongue - ouch). Spark plugs changed within the last month. Had it to three shops so far, codes come up. Happens at all speeds, 0-90 mph depending on load. From stop, stalls frequently, unless I floor it, in which case I waste tire longevity, risk tickets, and when it jerks violently, it's worse than usual. They've checked for vacuum leaks, changed a few vacuum lines, changes nothing. Any help would be greatly appreciated, as I live 102 kms from work, and the drive is made excruciatingly long because of all the hills, and if it always feels like this, I don't want to bite through my tongue again.

Answer: It sounds like you have a ignition coil housing that is starting to fail, replace with new to recheck system.

Question: 2002 Ford Thunderbird mileage: 86,000. For the past 6 months I noticed that as I accelerate lightly and the car reaches above 35 mph if I hold the accelerator steady the rpm slowly decrease and the engine begins to vibrate until I let go of the pedal a bit and give gas again. During the winter when it's cold, the car would run well until it warms up. I changed all filters, and many people tell me that it could be the EGR valve. Should I try to clean it or replace it? It feels as if the engine is losing power during cruising condition but while driving with full acceleration the car runs fine.

Answer:   It sound like you need a major tune up including spark plugs, spark plug wires, fuel filter and air filter. Replace as needed to repair problem.

Question:   21993 Saab 9-5 Wagon I4 Aero mileage: 82,000. The problem with the car is that when you step on the gas it goes to about 15 then it loses power. My daughter says it spits and sputters. It seems like it is not getting fuel. Could bad gas cause this? We have changed the fuel filter, plugs, wires, and checked the fuel pump. We put some fuel injector cleaner in the gas tank and my daughter said this seems to be helping but it still is not running right. Any advice you can give me would be appreciated. Is it difficult to change the fuel injectors if that is the problem?

Answer:   Check the catalytic converter for blockage. It sounds like the catalytic converter has failed and is blocking the exhaust system. Replace catalytic converter with new to recheck system.

Question:   1992 Ford Mustang mileage: 90,000. Hi guys.. I have seen other articles here with VERY similar symptoms, so I apologize for a repeat, but here goes, two problems. The car starts very well, hot or cold, idles pretty good when cold however pretty rough when hot. The idle when the car is sitting still is about 550 RPM, but if I let the car roll in neutral 5-10 MPH down hill, the idle jumps to about 2000 without touching the accelerator (note - it also smoothes out). Once I push the brakes and slow the car back to 0 Mph the idle settles into a rough 550 RPM or so. This symptom is very consistent and reproducible. The second issue is occasionally the car flat out dies. When it's cold and I can stay moving (i.e. Freeway 55 MPH and no traffic) it runs great. Once I have stopped a few times either in traffic or just around town, it will die unexpectedly. The only recourse is to put the car in neutral or park, turn the key off and start. It always starts right up. It does sometimes die again immediately after starting, other times, away I go down the road. Any help on either or both of these problems would be appreciated.

Answer:   You have a idle air control motor that is malfunctioning and needs to be replaced. Replace with new to recheck system.

Question:   2002 Chevrolet S10 Blazer, mileage: 85,899. It has been running rough lately and a lot of fuel has been coming out of the tailpipe and the smell of fuel is very extreme. I have had it put on the computer to check everything. My husband has changed all the spark plugs; the left side was bad, the right side was good. We even had the fuel injector cleaned. But when we did this it really started to run rough. Any suggestions on what may be causing the problem? I am putting too much money out for fuel lately.

Answer:  Check the fuel pressure regulator. You will probably find that the diaphragm has ruptured allowing raw gas to be drawn into the engine. To repair replace fuel pressure regulator with new to recheck system.

Question:   1999 Toyota 4Runner mileage: 74,000. My 4Runner has started to miss/stumble when accelerating, doesn't seem to miss/stumble once you reach a constant speed, doesn't miss/skip when idling, just had it tuned up not to long ago (it should not need another one this soon) when going up hills there is a strong smell like sulfur/rotten eggs, I think it's my catalytic converter, short of replacing it is there anyway to unplug one? Please help, my husband says it isn't the catalytic converter, could it just be a problem with fuel mixture, it is fuel injected.

Answer:   It appears you may have a fuel pressure regulator. Remove vacuum line to check for the presents of fuel. If so replace with new to recheck system. This is also causing the smell out of the exhaust.

Question: 1998 Nissan Sentra mileage: 120,000. Car sputters and jerks/lurches in a rhythmic fashion (like I'm revving the engine even though I am applying constant pressure to the accelerator). Typically does it when I get to above 40 mph, but has done it accelerating from a dead stop and other speeds as well. Also, doesn't do it all the time. Have changed fuel filter & replaced air flow sensor. Nothing. Mechanic has said it is neither "gunk"/moisture in the gas tank, nor fuel injector problems. We are at the point of fishing...HELP!

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: 2002 Cadillac Seville mileage: 97,000. I took the car to the Cadillac dealer and they performed a 100,000-mile tune up which consisted of replacing the spark plugs, and fuel filter. They also performed a de-carbonization service and serviced the E.G.R. and throttle body parts. The engine continued to run rough and when I took it back they re-secured a coil control wire and performed idle learn. The engine continued to run rough, so I took it back to the dealer again. This time they stated that a spark plug was defective causing an intermittent misfire. They replaced No. 1 plug, scoped ignition system, tested injector output and ran complete fuel systems test. All OK They stated vacuum gage fluctuated at idle; fuel mixture is lean at idle. Also stated that an internal problem may exist at valve guides. I was not satisfied with their analysis as the engine continued to run rough. I took the car to a local mechanic with 30 years experience and asked him to have a go at it. The engine still runs rough! I would appreciate your input as to what may be causing the problem.

Answer: Check the cylinder #1 compression if it is over 110 pounds. Try replacing your #1 cylinder fuel injector. If under 110 pound there is some internal engine damage and a engine inspection is required.

Question: 1994 Nissan Xterra 4WD V6 mileage: 58,000. My question is this. I have been having some trouble with my truck sputtering very badly. It really acts like it is not burning all the gas. I changed the spark plugs and fuel filter. This did not help. Then I changed the 02 sensor. This did not help either. There is a really bad exhaust smell, like un-burnt fuel and there is some really black suit all over the back of the car. The car does not run hot, but the exhaust pipe is hotter than normal. One time recently the catalytic converter light came on. Could it be a problem with my ignition coil or something else? I am sure that the fuel is getting there ok, but I just don't think it is being fully burnt. Please help. Any help or advice you can give will be greatly appreciated. Thank you

Answer:   It sounds like your EGR valve (exhaust gas recirculation valve) needs replacing. Replace with new to recheck system.

Question: 2001 Dodge Neon mileage: 94,000. Engine is running rough and at times, producing very little power. I took it to an authorized service dealer for diagnosis. They said the "upstream oxygen sensor" has failed and needs to be replaced. That sounded fine to me. Next, citing the mileage of the car, the guy earnestly mentioned that the timing belt should be replaced. I understand the implications of a failed timing belt but I was rather surprised that it would need replacing at only 64,000 miles. Any thoughts?

Answer:   In most cases the manufacture recommend the timing belt be replaced every 60,000 miles. And when the timing belt drives the water pump replace the water pump also.

Question:   2001 Buick Park Avenue mileage: 104,000. Problem, About 45 mph when converter clutch (T.C.C.) comes on, car starts jerking and bucking hard. Acts like bad ignition module under engine load.  When taking off from a stop or trying to maintain freeway speed, car keeps going slower. More gas given, slower it went. Acted like a carbureted engine with a bad accelerator pump. Then it would suddenly take off. The next time you stopped and/or if you turned the a/c or defrost on, same thing again - only much worse. Replaced throttle position sensor (T.P.S.)  Replaced oxygen sensor, fuel filter, fuel pump relay and had injector cleaned. These are all related to one common reason - these problems only happen when it rains. I have checked all the wiring, can't find and exposed or corroded wires or connections, checked ECM - dry as a bone. After it quits raining and dries up car runs great. HELP!

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