Repair Topics / Engine-1 / Engine-2
 
Car Engine Questions and Answers

• How to tune up your engine
• Why does my engine stall?
• Why is my engine running rough?
• Why wont my engine crank over?
• Why does my engine stall at idle?

This category contains featured questions as examples. They relate to most vehicles.

Question: 1999 Dodge Daytona mileage: 106,000. I bought this car a little over a year ago and it ran fine for a while with only a little burning of oil. Now the car smokes badly while at idle from the hood and from the exhaust! It has 146,000 miles on it. I plan on getting it rebuilt. If I did this and took care of the engine would it last for a while?

Answer: The answer is yes, if the engine you select is a good quality rebuild. Not all rebuilds are the same. It depends on the re-builder. Ask for references or at least ask friends and be sure you get a warranty.

Question: 1995 Oldsmobile Silhouette mileage: 64,000.  A rod went through the engine destroying the engine.  The last mechanic that worked on the oil gaskets said it was a "coincidence" it happened, it’s a GM product, and no one's fault.  This is just not acceptable to me.  Can you tell me what would cause this to happen?  I have to have a rebuilt engine, and have paid this mechanic a lot of money.  I need answers.   Thanks

Answer:   Normally an engine will “throw a rod” if it gets low on oil.  Just replacing gaskets should have nothing to do with your problem.  Whether or not it is the mechanic’s fault depends on which gasket was replaced and when the problem occurred.  If the oil pan gasket was the one replaced and the mechanic failed to refill the crankcase with oil, the engine would fail within a very short distance (under 2 miles).

Answer: If a major tune-up has not been done recently, that could be the cause. Replace the spark plugs, plug wires, fuel and air filters, etc. Also, replace the oxygen sensor. In addition, service the fuel injection system. Clean the carbon deposits from the throttle bore and idle passages. With 100,000 miles, you may have a partly plugged catalytic converter.

Question: 1999 Buick Century mileage: 89,000. We recently replaced our engine and within a short time, it acted up on my wife in stop and go traffic. The people who replaced the engine then replaced the coil packs. This seemed to work for a while, but it started to backfire and lose power when my wife was in stop and go traffic last week. I was kind of not sure that it was doing this because I wasn't there. I drove it to and from work for about the next week and a half and last night it did it to me. It was backfiring through the carburetor I think and I didn't see any smoke. When I tried to give it more gas it acted like it had no power at all and soon died. I let it sit for about ten minutes and then I drove it the rest of the way home (about a block and a half) and it started to do it again just as I got in the driveway. We don't know what to think and we're not sure if the guys who replaced the engine know either. Please help! We have only put about 4,000 miles on it since the engine was replaced. This has put us $4,000 in debt.

Answer: Unfortunately, there maybe no easy fix. The vehicle must be scanned for trouble codes (OBD II) to pinpoint which system is failing. Then trouble shoot to repair the problem. Some possibilities are fuse pump or PCM (computer).

Question: 2004 Toyota Tacoma 4-cyl mileage: 30,000. Whenever I go to order parts they ask me what size engine 1.7 -2.4-2.7? I looked everywhere on the engine and I cannot find any of this numbers. Is it hidden somewhere?

Answer: The information is located on the EPA - tune-up sticker under the hood, or near the motor. If you still cannot find it, call your local Toyota dealer and give him the VIN number and they should be able to tell you.

Question: 1969 Triumph Spitfire, Mk3, mileage: 48,000. We have a '69 Spit that we are rebuilding, and the incomplete engine we inherited with the car has cylinder bores quite a bit larger than stock. We do not have pistons for it. Does anyone make aftermarket pistons for these engines in a choice of over-bores? Or, for that matter, are there automotive machine shops out there that can sleeve one of these small motors, in much the same fashion as some shops will sleeve American V-8s?

Answer: Yes. Any good machine shop should be able to help you. As for direction to go with new pistons, or to re-sleeve, we would go for the most cost effective route -- but stock parts can avoid unforeseen problems. One final thought, double-check your engine block and pistons to be sure they are the correct parts for your car.

Question: 1999 Chevy S-10 140,000 miles. I have to float the throttle to keep my power to drive also it starts hard for a fuel-injected engine TBI.

Answer:   (1). Start with a major tune-up which includes plugs, plug wires, cap and rotor (if applicable) compression check, fuel injection service (if applicable) fuel filter, air filter, oil change w/filter, cylinder balance test, (2). Check fuel filter, (3). Scan PCM computer, (4). Check fuel pump pressure.

Question: 1999 Chevrolet Cavalier, miles: 96,000 After the engine reaches normal operating temperature the engine will suddenly quit (diesels) when coming to a stop. It does not do this until after driving for a while. I have accessed the trouble codes and got a code #23 (MAT sensor problem.) I got this code from a Haynes repair manual. The illustrations in the manual are vague and generalized for several models and makes of cars and I am unsure of the location of this sensor. I believe it is on the air cleaner housing. Could the problem be carburetor and fuel mixture related? Also, how do you set the timing for this make and model?

Answer:   The MAT (manifold air temperature) sensor is located to the rear of the intake manifold slightly to the left. (Driver’s side) Your problem could be fuel mixture related. The MAT sensor may cause the problem. There is no timing to set. The diagnostic connector is located under the left side of the dash on the right of the fuse block.

Question:   2002 Isuzu Trooper, miles: 89,000 It failed to start today after driving regularly. I think it may have slipped time. When trying to start it popped and ran for a couple of seconds very roughly then died. Now it will not make any sound as if trying to start. While turning the engine over, I took the oil filler cap off while putting my hand over the opening. It was blowing quite a bit. I think I have heard that is a symptom. What do you think?

Answer: Perform a compression check on the engine. If all four cylinders are low (below 100) the timing belt has probably failed.

Question: 1999 Ford Focus, miles 120,000 It started running a little rough and the next day died on the way to work. I got it started, but it would only idle and the gas pedal did nothing unless you kept it all the way to the floor and then it would begin to rev up after a minute or two. It would then rev up and down normally until i let off on the gas peddle and then it would only idle again. I changed the fuel filter first and that did not help and then I changed the fuel pump in the gas tank and that did not help either. This is a fuel injected engine. What else can i do?

Answer:   Good job tracking the problem. You have done the basic maintenance on your fuel injection system. At this point, I would hook your car up to our electronic scan tool to check for any stored faults in the control module computer. Assuming, however, you don't have access to this tool, it's back to the trial and error method. Check the timing belt. It may have "jumped" a tooth. If that checks okay, next check the ignition system, starting with the pick-up coil, ignition module, and coil. When the cap is off the distributor, check wire connectors. Next check the fuel management components, oxygen sensor, map sensor etc. There is a remote chance you may have a plugged catalytic converter.

Question:   1999 Mazda B2200, miles: 142,000 on it. It has been missing (I think, the engine hesitates, and actually makes the truck shake) in forth and  fifth gears, especially in the morning and going up hill. If I let off of the gas, or down shift, it helps but still struggles to get up hills. It is only  really noticeable on the freeway. I just replaced oil & filter, air filter, plugs, wires, dist. cap & rotor button. I am still having this problem. It doesn't seem to happen in gears one through three (or is not that noticeable). Any ideas?

Answer:   Two tests should be performed. A compression test and a cylinder leak-down test. Depending upon the results of each test, you will probably find a blown head gasket, a burnt exhaust valve, or broken piston rings. If you find any of the above, and due to the 142 thousand miles on the motor, you may want to consider overhauling the motor. 

Question: 1995 Mercury Mystique, miles, 78,000 I did a full tune-up including new wires, plugs, fuel filter, air filter.  I drive very little, about 1.5 miles a day.  The car has no off-the-line power but when I bring the revs up, it is fine.  I have no clue as to what it is.  It has only 45000 miles on it.  Any suggestions?

Answer:  Your car has a computer controlled engine management system. If the M-I-L warning light on the instrument panel has been on while driving, then a diagnostic check must be done with the proper equipment. If the light has not been on I would first do a compression check then test for a restricted catalytic converter. If your car has a automatic transmission have it checked also. 

Question:   1999 Dodge Intrepid miles: 67,000 The car runs great when it cranks. I have replaced the Ignition Coil and Plug Wires, but every now and then, the car will quit running while riding down the road or won't crank! If I wait a little while and it cranks (sometimes waiting for 5 minutes or up to 2 hours). I don't believe it's starving for gas because the tank is full and when it runs, it runs great! I had a friend who is a mechanic and he put some type of equipment on the car, which would show any error codes. It showed nothing! Is there anything you can recommend checking?

Answer:   The intermittent problems you described are hard to diagnose. If possible, the car should be checked when the problem is present. When your car stalls, check for spark at the spark plugs, to isolate trouble in the ignition system. Next, test the fuel pressure to eliminate fuel pump and pump relay problems. You said you replaced the ignition coil; did you replace the ignition module as well? Was the crank angle sensor replaced (part of the ignition system)?

Question: 1999 Ford F-150,miles: 145,000 two wheel drive, 4 speed manual transmission with the following symptoms: on transition from light to medium loading, the engine experiences excessive pinging. At low rpm, the ping sounds more like a solid knock. It sounds like it happens on one or two cylinders. Base timing was checked and found okay. On retarding ignition timing approximately 10 degrees the pinging is minimized with occasional low rpm knock. Otherwise, the engine runs and sounds fine. Sometimes with base timing at its recommended setting of 10 degrees before top dead center, the engine would operate properly with no pinging on heavy loading. Does this engine utilize a knock sensor and if so where is it located? Your assistance is appreciated.

Answer: The problem you describe may be the result of one of the following:

1. Carbon deposits in the intake ports and or combustion chambers,
2. Spark plug wire cross fire,
3. Harmonic balancer ring moving giving false timing marks,
4. Improper gasoline octane.
   Your engine is not equipped with a knock sensor.

Question: I've got a Ford Granada 2.4 v6 I, and it has a flat spot at about 2,000 rpm. Apart from that, it drives perfectly well throughout the rev range. Any suggestions?

Answer: In order to diagnose your problem, it is necessary to know what year your car is.

Question (follow-up): Thanks for your response to my car problem. I am sorry I did not supply enough information about my car. The car is a 1989 Ford Granada 2.4 v6 injection. The problem is that there is a flat spot or hesitation at about 2,000 rpm. I have checked every thing that I can think of: the air filter, the idle speed control valve, air flow meters, leaks in the intake manifold, and I have changed the spark plug wires. The spark plugs tend to look a bit sooty, so I think it may be a tuning problem. I hope this is enough information for you to diagnose the fault. All your advice much appreciated.

Answer: Check the EGR (exhaust gas recycling) valve. It may be stuck or the return spring is weak.
 

Repair Topics / Engine-1 / Engine-2

Replace Air Filter

Check Engine Light