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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Hyundai
Satisfied Customers: 44534
Experience:  16 years of experience
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2.0 engine 2001 hyudia elatra engine won't idle, smooths out

Customer Question

2.0 engine 2001 hyudia elatra engine won't idle, smooths out after 1500 RPM pulling codes PO455, PO133, PO422, UOD80 AND POO5O. I have not been able to make a determination of repair needed. Need some help. None of these codes are notmally critical enough to cause them to constant misfire and run rough at idle.
JA: Have you seen the misfire code before? Has the car been stalling?
Customer: No. The oil was changed at a drive thru oil bay and the problem occurred shortly after the oil change. The engine was hard to start when it was picked up from the oil change place and started to run rough on the way home, then the wngine finally quit running. The engine now will only run after 1500 RPM.......I am lost on this one???
JA: What is the model of your '01 Hyundai?
Customer: Elantra 2.0 16V
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes, I am an ASE certified tech although I have not worked as a tech professionally for over 25 years. I am retired. So for I have checked the charging system to assure proper 12.4 diagnostic voltage. I then pulled the codes and then have been researching my findings. I also performed a physical inspection to rule put any visual concerns to address.
JA: Anything else you think the mechanic should know?
Customer: That is all I know at this time. The only code I could not find any info on was code UOD80. None of the codes are critical enough to make the engine function as listed.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Hyundai Mechanic about your situation and then connect you two.
Submitted: 5 months ago.
Category: Hyundai
Expert:  Chris (aka- Moose) replied 5 months ago.

Welcome, I'm Chris (aka Moose).

I am saying sorry for the delay as a blanket response for all others online today that passed on helping on this concern. I just go in recently and caught up and am now checking on the long waiting customers first. Do you still need help?

Customer: replied 5 months ago.
Hi Chris, I still have not been able to get this motor to smooth out at idle. I did find that if I unhook the wiring to the TPS the engine idle smooths out. I am not sure how this is happening. I also replaced the EVAP purge valve as it seemed to be leaking.
Expert:  Chris (aka- Moose) replied 5 months ago.

So at idle it is misfiring?

Have you done any of the diag steps for the codes you have, if not are those needed?

Above 1500 rpms it will drive perfectly fine?

Customer: replied 5 months ago.
I will have to get back with you tomorrow as the car is @ my daughters house about 150 miles away. I will be back working on it again tomorrow morning. I will perform a few more drivability tests then. I have had several different people tell several different things that might possibly be the problem ranging from a simple MAP sensor or MAF sensor to the defective purge valve or leaking vacuum lines. Someone else suggested a possible defective intake manifold gasket. I physically inspected every vacuum line I could find in the engine compartment. I also replaced the EVAP purge valve as it seemed to have a slight leak when I pulled a vacuum on it. I cleaned the throttle body and checked the TPS for resistance although I do not have the specs for the TPS, I just made sure that the variable resistance factor was operative. I checked the intake manifold for a vacuum leak. Also someone suggested the CAT Converter may be stopped up. But I think that if it was the CAT that was causing the problem, it would effect more than just the idle. I pulled the codes again after I made the repair I listed and found no change P0445, P0422, P0301, P0304, P0300,U0D80, P0050. Also I searched the internet but could find any info on code U0D80.
Expert:  Chris (aka- Moose) replied 5 months ago.

No problem, report back when ready.

Expert:  Chris (aka- Moose) replied 5 months ago.

Hello again Chris here,

I am contacting you because the post has not been closed or rated. We have 7 days to get a post rated before it times out. When a post times out, that means its no longer on my active list (if you reply I never know it.) You have already paid the fees to get this question answered, but it appears your not pleased, or need more help.

Let me help some more. Is there anything else you feel I could offer so you would be pleased with my help. I have the option to call you if that would be better.

Thanks Chris

Customer: replied 5 months ago.
Hi Chris, After cleaning the throttle body, IAC, and the map sensor. I also validated the TPS was at correct vales. I then checked the EVAP canister purge valve to assure it was functioning properly. The valve is in the normally closed position and when I pulled a vacuum on it held as it should. I am not sure how to check the valve to assure it is opening or how to check the wiring to the valve to assure the proper voltage is being applied. I also found out that the fuel tank has an extreme hard time accepting fuel when filling it. I checked the EVAP canister to assure it was not stopped up. The vent valve was in the open position. I am not sure how to check this valve or what other lines to check for stoppage.
Expert:  Chris (aka- Moose) replied 5 months ago.

So the only concerns that remain are slow fuel fill ?

Customer: replied 5 months ago.
Chris, The engine has really got me. After all the work I did the is started and idled as it should for about a minute or two and then started running rough and missing just as it had before I worked on it. . The unit does not have a MAF sensor so the AIC and the MAP along with TPS are the only monitors to the ECM. I don't like just changing parts, but this one has me thinking that maybe I should go ahead and change the MAP and the AIC. Your thoughts.Question are the charcoal crystals in the charcoal canister suppose to be able to fall out of the hose ports when the hoses are unplugged from the canister and it is held upside down or if you blow thru it?
Expert:  Chris (aka- Moose) replied 5 months ago.

You should not be able to get the charcoal out of the EVAP no matter which way it is turned, it should have screens to prevent that.

The idle air control valve is going to be the most likely cause for not able to sustain idle.