I am having the exact same problem with my 2001 Hyundai Elantra. I was told that the engine code that comes up when the sensor is on is called "Absolute Pressure In The Manifold". I was told by a "Hyundai Specialist" that when that code comes up it usually means that the seal on the manifold is Fuct. When my mechanic checked that out for me he had noticed that my manifold had 4 cracks in it(can varify cause he showed me). He replaced the manifold and gasket. The car ran fine for about 2-3 days and since then the problem has since come back and my check engine light will no longer go on/off it only stays on. Because of the check engine light always staying on I have noticed that on many occasions my car will hiccup many times in a row. The only way to stop the hiccup I have noticed is to take my foot right of the gas for approx. 2-3 sec then car will continue without hiccup(till it happends all over again). All in all I have been having this problem now for approx. 1 year and if there is somehow someway it could be repaired I would appretiate it.
I have a 2005 Elantra and I am having this issue. Was anyone able to fix this? My son believes it is the coil pack....
×
If everything you described is true, then there's a strong suspicion it's the ECU. Whenever the 'CHECK ENGINE' light comes on, the ECU (Engine Control Unit) sets a Diagnostic Trouble Code (DTC). These codes identify the particular engine management system which caused the light to come on. You'll need to use/find an OBDII (On-Board Diagnostic) Scanner to retrieve any code which have been stored in the ECU computer. Since you stated there were no trouble codes (DTC's), there's one last thing to try... ZERO out the ECU (do this by disconnecting the battery cables from the battery posts... connect the cables together for 30 seconds (this ZERO's out the ECU). Afterward, reconnect the cables to the battery. If the problem recurs (and there's no DTC's), the problem is in the ECU.
No damage will occur to the electronics... just short/connect the battery cables ONLY to each other for 30 to 60 seconds.. this will dissipate the charge in the ECM/ECU and ZERO out the computer's memory... subsequently, the computer has no other option but to BOOT from its EPROMS (erasable Programmable Memory) so there's nothing but ORIGINAL manufacturer software loaded into the computer's memory... If you know anything about computers, it's the difference between a 'WARM' boot and a 'COLD' boot.
The ECU is not designed to turn ON the CHECK ENGINE light without recording a DTC... If it does turn on the MIL (malfunction indicator lamp) without recording a DTC, there's something wrong with it.
You mentioned the mechanic thinks the fuel pump is alright, did he check the fuel pressure when this problem occurs? The pump pressure could be 'intermittent' due to possible over heated electrical connection in the fuel pump circuit. I've seen this before. As the connection heats up (poor connector contacts/pins), the resistance in the circuit rises and the pump doesn't get 'full power' from the electrical system and will intermittently shut off. This lowers the fuel pressure in the fuel injector rail (can definitely cause P0?00 codes) as the fuel mixture starts to become 'LEAN." I've seen this happen before. While monitoring the fuel pressure over several minutes, it abruptly started to drop off and then, just as abruptly, came back up. Inspection of the fuel pump connector pins (outside and inside the pump) revealed overheated (melted/discolored) plastic connectors which house the electrical pins.
You mentioned your mechanic "wants to know if it could be the coil pack i.e. if there is crack or something else. He says he's seen it (not on Elantra though) that the car would stop, then restart. Turned out to be the coil."
Examination of the coil packs can only be done by oscilliscope on the Elantra... A bad coil pack setting a P0?0? will consistently be either P0101 + P0104... OR P0102 & P0103, since 1 & 4 use the same pack, as do 2 & 3... to think it's 'BOTH' coils is a rare occurance in the Elantra -- check the connector pins to the coil (pin tension). I'm leaning more and more toward 'electrical' connections since the only codes being set are misfire codes. The 'freeze-frame' data should lead you (give you a hint) as to which engine management system may be causing the problem, especially when you're only getting P0?0? codes - I still suspect fuel pressure/pump. Note: I have seen the crank position sensor (CKP - One very rare case), cause the symptom you are experiencing. However, on more than one occasion, I have found connector pins which were not fully inserted into their housings (loose electrical connections) which create many different kinds of symptoms, especially when they are 'ground' connections. Like I said earlier, my suspicion is still the fuel pump/pressure. The only way to eliminate the fuel pump is to verify the pressure is 'good' when the problem occurs -- then it's some "other" engine control circuit.
×
6,030 views
Usually answered in minutes!
Thank you very much for your answer. Just one question: do you mean short the battery cables to erase the ECU codes? Would shorting the battery damage any other electronics?
As a follow-up, assuming the ECU is not faulty, is it possible that the check engine light can come on without a code being registered by the ECU?
Thank you very much for your replies. Everything is very clear now. I will try the fix and report back.
Thank you again for replying.
Your advice made a lot of sense (since the ECU controls the check engine indicator at all times), so I expected good results. My mechanic shorted cables for over 60sec. Reconnected, started the car but the problem is still there. In park, car starts, no check engine indicator, runs a few minutes (2 or 5 or 25)then just turns off. Check engine indicator flashes before car dies. He checked for codes again, he got P0?00. He wanted to ask you if it could be the flywheel that messes up the crank sensor.
Tomorrow he will change the ingintion switch. Big puzzle this one.
Thanks again. I'll pass your advice and let you know.
BTW, do you at all suspect the ECU being faulty?
HI, I have an update. My mechanic checked the pump pressure while the car was running for over 20min. Pump pressure is OK. Also, all connections in the fuel pump circuit seem ok (all pins inside and outside). He also looked at other general connections/wiring (don't know which), all seem clean.
Had a problem with the power lock not working on the driver's side, thought that may be affecting it. Checked all door harnesses/wires, nothing bad.
He wants me to ask you if it could be the coil pack i.e. if there is crack or something else. He says he's seen it (not on Elantra though) that the car would stop, then restart. Turned out to be the coil. Also, assuming it's the coil, would it manifest the effects mentioned before (i.e. check Eng lt + P0?00 code = intermitten shu-offs etc?
Again, thanks for the help.
Thank you, I'll pass the message. Tru, the pump pressure was good but the car was running, one time for over 20min so it did not happen while the problem occurred. The thing is, now when it happens the car just shuts off so.
Anyway, went ahead and changed the coil pack. The car has been running for a whole day, so far with no problem. I am keeping my fingers crossed. Will keep you posted.
Thanks for the input. I'll ask him to check the manifold. Right now (more on a hunch) he has changed the coil. He said the car run for day without any problems (used to just turn off very often lately, from idle). He also drove it and no problems. But then again, the minute I take over it'll probably crap out on me.
I just hope I don't have to live with having to play with my foot and the gas pedal.
BTW, now that you get a staedy light, do you get any codes? If so what?
I have a 2005 Elantra and I am having this issue. Was anyone able to fix this? My son believes it is the coil pack....
×