Yes I've inspected the air filter area from inside out and I couldn't find any abnormality there.
One more thing which may give you some hint. The original problem I had was the codes 303 and 507. At that time I was mainly working on fixing the missfiring issue with cylinder # XXXXX I resetted the codes by disconnecting the battery terminal for sometime. As I restarted the car and took a ride on it I noticed that the engine hesitation because of missfiring was still there. The other thing was that the transmission didn't want to shift. I dragged it to high RPM where it shifted to second and then same dragging for the third and on. After three four shifts the car started shifting normally. So again my concern returned back to code 303 and 507.
I restarted working on the issue of missfiring of cyl # XXXXX The ignition/spark system to everyone especially the third one looked ok to me. Since the engine sound is normal and the 3rd's compression is also normal I suspected injection system. The injector's coil was found to have normal impedance (17.5 ohms) and so this completed my physical inspection because now I only have to take my car to my mechanic so he can dismantle the injector and see if it is physically stuck inside. Now as I am done with my inspections (injector coil impedances, ECM's injector firing voltage...) I found that my car started growling to 3500RPM as I start it. This wasn't the case before. The car wants to go to this RPM and so as I apply the gear it revs down to 1500 RPM but I have to apply brakes hard to stop the car because the idle speed is so high that without any throttle my car goes to 45mph. The other major issue is the transmission shift hasitation is back now. I was expecting that the transmission valve will calibrate after my ECM reset but after doing it again and again more than 20 times the shift delay/hesitation is still there. It doesn't shift except at a very high RPMs. The second shifts at 2500RPM and third shifts at 4200RPM.
This is a brief history of the problem. I've inspected the TPS and it physcially looks snug fit and intact to me but it may be internally damaged which I doubt as there was no reason for this thing happening. Let me know if you need more info.
No but the brand new plugs and distributor wires show that it will not make much difference because the spark strength is strong in all the cylinders. I hear the sparking noise whenever I disconnect any wire from the plug while engine is running. Let me know what else can I do?
has the valves been adjusted ?
they are to be inspected every 60 k and a tight valve will cause a cylinder miss fire.
i see this all the time on our cars at work. im betting the valve are way out of spec.
As I said before the engine sounds normal and the car has been missfiring for about two years now as mentioned to me by the previous owner. It has been serviced many times. Could the growling high speed i.e. 3500 RPM and code 121 relates to a bad TPS? Just a reminder the current codes are 303 and 121.
ok lets try and correct 1 problem at a time.
lets start with a valve adjustment since their is valve adjusment problems this motor.
Yes the valve has been readjusted but the issue is still there. In the meantime I've replaced all the injectors, the fuel rail and the TPS while spark plugs and wires were already replaced in the beginning of this issue few weeks ago. The car still throws 303 (missfiring) and 121 (TPS). The car starts and idle at 3500RPM. The shift points have moved up to a point where 2-3 and 3-4 shifts feel like engine is about to max out in speed when shift occurs. If I reset the ECU from the battery, it starts fine and not shoot to 3500RPM but keeps fluttering the RPMS from 1500 to 2500 as if it (ISC) is in learning mode. You put it in drive and within a mile or so you feel like there was some problem and it didn't find the tuned ISC position. It starts shooting to 3500RPM again and the shifts are in trouble. Please let me know soon as this problem has eaten alot of my time and money and I am trying to get it fixed ASAP.
the coolant system is full ?
Thanks I'll wait.
When I reset the ECU and restart the car it keeps hunting for the idle rpm from 1000 to 3000rpm. If I keep it running like this for minutes and hours it just keeps doing that. It never finds a good idel speed for the engine. Changing the idle speed shows that the ISC motor is working fine. Anyways I want to know if there is any special technique to make the ECU learn the idel speed? Once this is done I'll move forward to other codes and fixing them but let me try first thing first. Let me know soon.
I felt missfiring. Applied the scanner that read the code 303 (for cyl 3) and 517 (idle overspeed). Replaced all the plugs and the wires and resetted the ECU. It started ok but stayed at a higher idle RPM around 2000rpm. I took it to a ride and noticed that the shift points have been moved way up almost to the engine max rmp for 2-3 ad 3-4 shifts when the shift occurs. I had to do this once and then the engine/power triain learned the settings and started shifting fine.
A couple of days later when I wanted to fix missfiring I resetted the ECU and now I started getting new codes 303 and 121. The car would shoot to 3500 rpm as you start and want to stay there. I took a ride and found that the shift points have moved up again and even after shifting few times it never learned and kept the shift points very high. To remove 121 I changed it with a tested TPS. To take care of missfire I replaced all the fuel injectors and fuel rail. It never got better. Since then this is how the car is;
You reset the ECU it would try to learn idle but keep fluttering and never learn. You take a ride and CEL would pop up and the car would not shift untill the max engine rpm. You park the car turn it off and start it again. Now it just wants to shoot to the max engine rpm i.e. 3500rpm. Forward or reverse travel behaves the same.
With the help of a mechanic I've tested the ISC motor. It works fine. The TPS resistance and voltages are within range. MAP also looks ok. The air intake system doesn't look abnormal to me. I didn't dismantle anything and so air or fuel leakage from any seals is highly unlikely.
The concern that I have now is that I want to be able to see that the car shifts fine and if there is missfiring issue that can be taken care of later. No idle or hunting idle speed and abnormal shifting looks all related to me. Please give me your best possible causes for these problems before I try last resort of taking it to the dealership.
Let me clarify it before I do anything wrong. So you want me to
1. Disconnect the battery terminals from the battery
2. Short circuit the positive and negative cable connectors (not the battery which will explode) to drain all the ECU residual charge.
Is this what you want me to do?
Well I did exactly what you've asked me to do. It did start normal like there is no problem with a constant idle speed of 2000rpm. After about five seconds it started fluttering again between 2000 and 3000rpm the sameway as before. I took it to a ride and that felt different too as if the problem is solved i.e. shifting was normal. No engine overspeeding or overspeed shifting but after a mile or so it popped up 121 without any reason and then it started behaving the sameway. I drove it for about five miles but so far it has not popped up 303 but overall everything looks exactly the same.
Bottomline this has proved that the problem is still there and that even after carefully clearing all the codes the codes popped back on showing that the problem is still existant.
I started wondering about a problem but then I realized that it couldn't be true. That may be more than one cylinder i.e. two are missfiring for any crazy reason and that is why the engine flutters between 2000 to 3000rpm when there are no codes and ECU tries to find a good idle speed. When you start to drive the car it shifts fine from 1st to 2nd and 2nd to 3rd i.e. ECU gets the shift speeds and other parameters to shift fine. I don't know but something either high throttle or going to a higher gear triggers the 121 and then it just goes crazy. Now the ECU only wants to see the car at the max engine rpm. May be the engine code is written in such a way that if it sees error code 121 logged in it just wants to see the engine idle at highest idle speed. I've tested both of my TPSs and they show no problems in resistances or the ECU connector in voltages. So I am not sure what to say about this problem. Let me know if you have any clue or you want me to try the last resort now?
There is a TSB on updated fault diagnosis MIS-FIRE that includes a valve job, but the basic P0303 it wants you to take a look at the (colil resistance) I cannot even find a code 517... 507 is a valid code related to ISC control , it ends with (REPLACE) ISC or ECU
I say get a used (ECU) and re-test, there are two many issues and failures to waste time.
Take a look at the updated TSB testing for (ONE) cylinder mis-firing.
Spending so long to solve the issues and still sitting almost where I started. I was very frustrated this morning with the state of my car and so I took it to the local dealership. After spending sometime they found out that the third cylinder intake seal is torn into two pieces and so had a leakage which was the cause of 303 and may be the TPS. I wish if there was a simple way of diagnosing it and fixing it sooner.
Yes my freind there is a FACTORY BULLETIN on INTAKE GASKET PROBLEM, and yes it was a difficult problem to resolve. Taking the car to the dealer was the best solution, I am so glad you got it resolved...
Well I am confused you posted last you took to shop and had it fixed?
No I didn't get it fixed from the dealership because they were too expensive. I've already spent alot on the problem. I would like to get it fixed from my own mechanic which will save me some time and money. The questions in my last post were for my reference in case if my mechanic messes up anything in this job. I am going to repeat my questions here;
1. How do you test the intake gasket leakage?
2. Do you know the tightening torque on intake manifold screws?
Any illustration on dismantling and assembling of the intake manifold would be very helpful and highly appreciated.
First I wanted to appoligize I did get kind of upset on this question but this P0303 Code is the number one complaint in every Elantra forum and every person has replaced every component on the car, fuel injectors, sensors, spark plugs, plug wires, coils, and nothing fixed this issue but the INTAKE MANIFOLD GASKET ...
To verify after vehicle is warmed up you lightly spray CARB CLEANER near the base of the INTAKE MANIFOLD (caution is highly flamable) and listen for a distinct RPM CHANGE. Regardless replacing the intake gasket and clearing the codes is the repair for this issue.. The repair is very straight forward, simply remove and lay to the side everything connected to the intake. And the only concern is (let the engine cool) before you do the repair because fuel will leak when you (sowly release) fuel pressure from the fuel lines. The fuel is under high pressure so lay a rag over the line while disconnecting it and slowly disconnect the fuel line.
The bolt tourque is (12- 17 FOOT POUNDS) I could not find any VISUAL reapair procedures in the FACTORY SERVICE GUIDE, I tried.
Thanks for your helpful comments and documents.
My mechanic has been delaying the job because he is too busy and so I am going to attempt replacing the gasket on my own with the help of a handyman friend who will also partake in the job. Please let me know;
1. After removing the intake manfold body and removing the old gasket, unless there is any damage to the mating surfaces of the manifold and engine, do I have to rub/rough or do any other preparation of the surfaces? I think I don't have to if there is no abnormality on those surfaces.
2. Should I apply loctite or any other special sealant on these two (gasket) mating surfaces?
Please give me any tip or tricks for the job.
Noy really you want to remove the old gasket material gently from both surfaces (be careful not to scratch it up) but I dont think this type of gasket wil stick to eitther side. Also just follow the torque specifications. Myself I sometimes put a small bead of (Black RTV) , not much, around the gasket in one small line just to ensure I get a good seal in case of inconsitencies in the mating surfaces.
You can doit NP, it's a very straight forwar repair, just make sure there are no chunks of gasket left behind and clean the surface off with like brake cleaner to insure its nice and clean. That's it...
Your following answer on Dec 03, 09 was very frustrating because I spent more than a month with the previous expert to find out the root cause of the problem but no one talked about the intake manifold gasket but after spending so much time and money replacing different parts in my car I was told that... read the response here;
12/3/2009 at 11:53 AM (10 hours and 11 minutes and 57 seconds later)
Anyways, the lower bolts of the intake manifold are kind of hard for me to reach and so I am taking the car to a mechanic to get it fixed. Once it is fixed I'll close this thread by this weekend.
Changing the air intake manifold gasket fixed all the problems. The missfire 303, the TPS 121 and other related problems in engine or transmission are all gone. I am ready to close this thread but I would really appreciate if you can post the procedure to reset the airbad in my Elantra 2001. The airbad light came on during some service for some reason and since then it has been on without any real hazard or any codes logged. Unless it is reset it will not deploy in case of emergency. Online search reveals the reset procedure of other Japanese cars but nothing on Elantra. Any help would be appreciated.
Hello, I am so glad...
Thats bad the thing about AIR BAG lights is that they are considered a safety issue and they are desingned so that you cannot clear the fault codes with a scan tool or turn off the warning light untill the problem is fixed. You can disconnect the battery or clear codes with a scan tool but (if the failure is a (hard) fault) the Air Bag light will instantly come on until the (problem is fixed), the system will not allow the light to be turned off if there is a failure.
Disconnect battery or clear codes with scan tool, if the light comes back on (there is no question a fault) in the AirBag system.
You have a Merry X-Mas my friend and thank you...
I talked to the dealership and as usual they want to charge more than hundred dollars to clear the light. I told you earlier that I took my car to the dealership for the last issue. They had three recalls done on my car related to exhaust manifold and airbag. They fixed the harness issues with the airbag as it was a recall (compaign) for them. Anyways, the light was there prior to taking the car to them and it is still there. They did what was mentioned in their books only. If I ask them to reset they will but charge me humungous for that. I called them couple of days ago and they agreed that there were no codes related to airbag and should be resetted fine thats the main reason why I started looking to reset it myself.
I have a Lexus GS300 1995. The air bag on that one came on once because there was an electrical issue. I reset it with the help of instructions I got from lexus forum. The instructions were very simple to follow steps of touching this wire for this long and then that wire for so long few times and it got reset. It stayed reset for more than a year than it came back on because I caused a short circuit while replacing the car battery and since there is no airbag code or fault I know I will be able to reset it following the same code.
Now I hope you understand where I am coming from. I've done the ECU reset many times but it doesn't help. It was the same with my Lexus GS300 because the airbag faults are not kept in RAM memory they are rather kept in non-volatile memory. That even after removing the fault you have to reset it by following a procedure either manually or through a scan code reader or airbag reset tool. I am still trying to see if there is a instruction for reseting the airbag code for my Elantra 2001.
Hello and I hope you had a good Holiday... You never get an easy code P0442 is EVAROPRATIVE EMMISION LEAK DETECTED it;s one of the hardest to figure out.