Free answers to troubleshooting and Auto Repair questions!
On this page you will find free answers to the automotive questions, which we selected as most interesting and helpful to all readers. As these are the most common questions, you will probably find the answer to your question among them, if you don’t please put you question by clicking here: firstname.lastname@example.org
169. Car don't rev
Anything I say would be just guessing as such fault may have a dozen of causes. I suppose that in your case you have your MILL on. That suggests that you have a problem with engine electronic management. So, suggestion is to make a simple diagnostic test with simple common OBD II diagnostic scanner and see where problem lies. If there are not DTC codes, or simply no problem with electronics management, you probably have a problem with your fuel pump which has to be replaced.
Thank you so much for your
168. Your books, and my problem with electric windows.
Hello i was thinking about buying your book. I am an electronics technician but i have 0 experience when it comes to car electronics. I have a power window issue with my car i have reverse polarity in the power window control switch. When i press down the window goes up and when i press down the window goes up. I took it to a shop they are telling me that the problem could be on the door or the main harness. Will your book help me resolve that kind of problem
Our books Automobile electronics & Car diagnostics give more than fundamental knowledge of vehicle electricity and electronics and thus are of the great help to professionals and amateurs to solve the problems and make repairs.
Regarding you problem with electric windows, it seems that everything works fine except the reversed polarity. The simplest way to solve this problem would be to change the polarity on door windows motors which are positioned inside the doors. For some reason, polarity was changed either on the motors or on the switches. The next thing, which is even simpler, you should try to do is changing polarity on the switches by exchanging wires from up to down position and vice versa.
167. High pitched noise - Kia Rio 1.5 tfi
Car making a high pitched noise when reversing sounds like needs oil but oil been checked.
Engine sound never changes either you drive forward or reverse. Thus, problem
obviously lies in the vehicle transmission or gearbox. If there is enough oil in
the gearbox, then you probably have a problem with worn-out reverse cogs.
166. Lambda probe
Recently on my Opel Astra Check engine light turned on indicating possible failure on engine electronics. In my Auto-Service Center, I was told that possible problem lies in fuel impurity what was registered by Lambda probe (O2 sensor). They reset the ECU and warning light did not come up for a certain period of time. After few months, Check engine light came up again.
The problem is that I am five hundreds miles away from home and I am not sure if I can continue driving with warning light on or do I have to visit the nearest car workshop for help?
Thank you in advance for your response!
Lambda probe, or O2 sensor, does not register fuel impurity or fuel quality. Check engine light will turn on for number of reasons regarding failures on engine electronics management. To resolve the real problem, vehicle has to be tested with appropriate car diagnostic scanner. If you are not noticing significant changes in your engine performances, you can continue driving and do the car diagnostics test when you get back home.
Namely, in case when engine can ran with failure of some electronic component without any danger to cause serious damages to the engine or endangering driving safety, ECU will switch to the Safe mode. This means, that ECU has installed defined program with written parameters to enable engine running even when not receiving data from certain sensors, for instance O2 sensor. When driving on Safe mode, you can notice purer performances and possible increased fuel consumption, but no harm can be done to the engine.
165. Erratic engine idle, KIA RIO 1.3 2001.
I have a following problem, erratic engine idle. Engine idle varies from 0-2000 RPM. I have cleaned the throttle butterfly valve, replaced O2 sensor, MAF sensor and idle stepper motor and also resealed complete intake manifold components. This problem exists regardless of fuel I use (petrol/gas). Compression ratio is OK, color of spark plugs is also OK, but problem does not go away idle varies from time to time without any order and it stabilizes by it self. Is it possible that problem lies in engine coolant sensor giving the ECU wrong information randomly? Before I did all mentioned work, I pulled out from ECU trouble codes P1166 and P1116. After I have cleaned throttle body and butterfly valve I noticed significant improvement, but problem still exists a bit less often. I also suspect that fuel filter may be clogged as it hasn’t been changed for last hundred thousands miles. Beside all this, I do not know how to recognize faulty engine coolant sensor (ETC). As I never encountered similar problem, please let me know where to start and what to do to solve this problem. Finally, your books are really great and I recommend them to professionals and amateurs.
Thanks for now!
First of all, replace the fuel filter regardless of mentioned problem as you may encounter further problems soon. On the other hand, dirty fuel filter most probably isn’t the cause of your problem. Even clogged filter will let enough fuel to feed engine during the idle, but engine will stall when accelerating.
Cleaning throttle body and butterfly valve usually solves such problems, especially after so many miles on the clock. As you have obtained certain improvement, cleaning was obviously needed. Coming back to the engine sensors, you also solved some problem by replacing Lambda probe (O2 sensor) as trouble code P1166 was related to it. Second code P1116 is related to engine coolant sensor (ETC). When you have already done so much work, you should also replace ETC sensor as it really does not cost much. Since you did not, let’s explain situation when this sensor causes erratic idling. This sensor works as resistor and changes its output voltage as engine warms up. If sensor is partially faulty it can randomly send wrong information to the ECU. Certainly, wrong information about engine temperature will result with wrong fuel dosage in engine cylinders. Either way, poor or rich mixture will cause erratic idle. If you go again to the chapter ETC sensor in my book “Automobile electronics & 4-stroke engines” you will find clearly explained and sketched how ETC sensor works and how to test it.
164. Air Conditioning does not work
I am owner of Skoda Fabia 1.4 Sedan. Two weeks ago I visited specialized workshop for vehicle’s Air conditioning systems to refill A/C system with gas. After refilling we have tested A/C and everything was in perfect order. System worked perfectly all the way, from workshop to my home. Next day when I turned A/C on, there was no cold air whatsoever. As I know something about cars, I pulled out power supply connector from compressor and checked power and ground terminals. I was quite surprised when I found out that there is no power supply on the connector.
I would appreciate your opinion about this.
Your problem is quite common and caused by gas leakage from the system. When gas pressure in the system drops the pressure sensor switches the compressor power supply off. Pressurized gas in the system mixes wit oil in compressor and lubricates its moving parts. Other words, if compressor runs with no gas it will not be lubricated and would not last long as any other machine running without lubricant. Therefore, pressure sensor is employed to prevent damages when gas leaks out from the system.
This time you have obviously wasted your money for refilling as job hasn’t been done properly. When gas leaks out from the system, must be a logical reason for that, system leakage. Before refilling, system has to be checked for leakages with colored pressurized inert gas. When filed with such gas, leakages can be spotted visually. After the leakages are repaired, system can be filled with appropriate A/C gas.
163. Stroboscope – timing gun
Could you please explain in details stroboscopic timing adjustment?
Stroboscope is a simple device used for timing adjustment on the vehicles mostly produced before 1991. Before the use of stroboscope, one should know what the spark timing exactly means, as well as what is the vacuum and centrifugal advance timing. If you are not sure how all this works, I would suggest you to study my book “Automobile electronics & 4-stroke engines” where all this has been explained in details.
162. Thanks for you answer,
but what should I do if fault codes are not found in ECU and problem still exists?
Such situations require quite a lot of knowledge. All faults related to engine electronics management are registered by ECU and displayed on diagnostics program. If there are no trouble codes registered, problem obviously lies in some mechanical or electrical failure. In such case, we should go step by step checking all possible causes which may be causing particular problem.
161. Problem with Alfa Romeo 145
I am a girl and absolute laic when automobiles are concerned. I decided to put some questions about problems with my car as I am getting different opinions about them from my friends.
My car is Alfa Romeo 145 2.0 TD 1998, with just over 100.000 miles, and my questions are as follows:
1. Alternator warning light is on all the time. Is this problem related to the alternator, or could there be some other reasons?
Problem is 99% related to the alternator which has to be serviced. Under alternator service we understand replacing the voltage electronic regulator and most probably Diode Bridge as well as both bearings on the rotor.
2. When accelerating, a big black cloud comes out from the exhaust pipe. People say that I have to change the engine oil. If this is the case, as I heard from the other side, the smoke should be bluish instead of black.
Yes, you are right. Oil has nothing to do with fuel overdosing what causes the black smoke. The problem with black smoke is usually related to worn out injectors, turbo charger underboost, incorrect timing and cylinder compression ratio. My suggestion is to find professional who will do some check ups and solve this problem. It can be also done by do-it-yourself method, but with considerable automotive knowledge.
3. When I start the engine during the cold weather it runs uneven and shakes from one corner to the other. If I do not keep my foot on the accelerator pedal the engine will stop running. Where is the problem?
Here we have also problem with fuel overdosing and all those above mentioned. In cold weather when engine is overdosed with fuel, engine starts running on two or three cylinders instead on four. This is the cause of uneven engine running. When engine worms up, it starts working on all four cylinders and stabilizes running evenly.
4. Very often I can smell fuel and smoke inside the car so much that I fear for my life.
Smoke and fuel smell inside the car are consequences of above mentioned problems. Bad condition of your exhaust system allows unburned gases to leak out from exhaust and entering inside the vehicle. Certainly, if you keep your windows closed it may endanger your health and even life.
5. Finally, where should I take my car for repair with certainty that I won’t be ripped off?
Make sure that you take your car to professionals who know what they are doing. These problems are quite straight forward. Right people will first examine your car and than make an estimate of cost with full specification of spare parts needed and time provided for such job.
Thank you for your time ad patience. I hope you will answer to my questions!
160. Diesel runs uneven
I own Renault Clio II 1.5 DCi 2003. This winter I had a problem with uneven engine running whenever I started engine from cold. I visited official Renault garage where I was told that fuel high pressure pump has to be replaced. I was not that much surprised with diagnose until they did not mentioned replacing fuel tank too. I do not know much about the cars, but this did not make sense to me. I wish to point out that I do not have any problems with my car except explained problem which occurred several times this winter when temperature was below zero.
All he best!
If you do not have any problems, beside mentioned, I do not see the reason why should you replace the high pressure pump which in most case has nothing to do with uneven engine running, especially during the cold weather. I would primarily test glow plugs. Glow plugs are parallel connected. In case when one or two glow plugs are burned, the rest of them will work properly, as they are parallel connected to the power supply. If this is the case, engine will start on two or three cylinders and run uneven for short time. As soon as engine warms up a little. The other cylinders, or cylinder, will catch up and engine will stabilize. Replacing the fuel tank does not make sense at all.
159. Some more horsepower
I am wondering if I can get some extra engine power without investment on box engine Alfa Romeo 1.5 with two twin carburetors. My idea is to lighten the flywheel and front crankshaft pulley by removing as much material from them as possible and finally drilling the holes trough them to remove even more weight. This engine I am installing in extra light buggy and every pound of weight is important to me as well as one or two extra horsepower.
From this engine is pulled out by factory almost as mush power as possible. By removing the weight from the flywheel you will definitely disturb the engine balance, even if you balance flywheel after modification is done. Besides, you will still have some extra weight on standard clutch assembly. If you wish to do it properly, there are specially modified units (flywheel + clutch assembly) offered on market for this purpose. But, by y opinion you won’t get out much of it in the sense of power as pretty more modifications on engine has to e done to increase the power. My suggestion is to use this engine as it is and do some simple modification to increase the power for about 7-10%. Remove original air filter and cover carburetors intake openings with hand made nets to prevent dirt entering into the engine. Replace standard exhaust system with sport flow trough mufflers. Freeing, by standard air filter, restricted air entrance in the engine and letting exhaust gases out of engine without restriction will bring noticeable life to your engine.
158. Questionable diagnosis
I have a problem, mechanic says, with catalytic converter. My car is a VW Golf TDi 1999. Here are the following symptoms: for some time I feel considerable loss of power. There is a delay when accelerating. Engine starting is quite difficult, just like when battery is flat. But, battery is new just like glow plugs. Two days ago, timing belt was replaced. Since than, there is almost not power at all, and it seems to me that turbine does not work either. I can not achieve higher revs than 2200 RPM even when I press the pedal right down to the floor. Mechanic says: catalytic converter is choking the turbine. I also heard if engine is overfilled with oil, catalytic converter can get clogged.
Are these all true, and what is your opinion?
By my opinion, here is the situation, more or less, quite obvious. If I understood correctly, problem occurred after the timing belt was replaced. It is not uncommon to make mistake while replacing timing belt. When belt tensioner is tightened, timing cogs may turn for one tooth forward. If check up was not made by turning the engine for 720° to see if timing marks match, there is a great possibility that engine is out of timing. Of course, there are more reasons for such engine behavior: MAF sensor, MAP sensor, catalytic converter, turbo charger, EGR valve, fuel supply etc. But in you case I would focus to improper timing belt installation.
Catalytic converter can be clogged and cause engine performance problems. It can be checked visually or by measuring exhaust gases pressure. Clogged catalytic converter can also slow down the turbo charger as there is not sufficient gas flow trough the turbine. With the basic automotive knowledge, one can assume that excess oil in the engine can not clog the catalytic converter.
To give an accurate diagnosis, at least fundamental knowledge is necessary.
For those who wish to know more: “Automobile electronics & 4-stroke engines”
157. One more questionable diagnosis
Hallo, I have Opel Astra from 1994 and having problem wit thermostat. It seems to me that thermostat is burned and I want to replace it my self. The question is: where is thermostat positioned on my car?
Well, I am not sure that I can help you much. From your question I can see that you are not very familiar with vehicle maintenance and repair. Namely, even beginners know where the engine coolant thermostat is positioned on such simple engine, at least roughly. Beside that, I doubt your diagnosis is accurate. I would say it is jus a guess. Further more, thermostat can not burn out. It is a valve working on bimetal principle and it can only be malfunctioning.
No hard filings, but before you spend some money on spare part for which you are not sure that need replacement, ask someone to help you out with basic diagnosis.
Will be continued soon!