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peterpete190, Auto Technician
Category: Hyundai
Satisfied Customers: 27814
Experience:  Auto repair Technician with 17 years experience.Past ASE and other certifications.
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The story is a bit, but here goes, a few years ago we

Customer Question

the story is a bit long, but here goes, a few years ago we noticed a "bump" happening occasionally as we were stopped at a light. The car is a 2002 Hyundai Santa Fe. 2.7l. shortly after that we began having trouble putting gas in the tank. as "that" problem got worse, we ended up at the dealer to have the evap system redone. fill pipe and all. $800.00 the bump continued. so now it's about a year past the evap fix and the bump is worse than ever, just getting worse over time.. So, since there have been no codes presented and the mil light works, and I do have and use my code reader, no codes. So far I have replaced, alt as it was getting weak anyway, coil pack, and plugs. To see if the catalytic converters were clogged, I removed the o-2 sensors, and ran it, still bumping, cleaned mass air flow sensor with CRC mass air flow sensor cleaner, cleaned the throttle body, checked the throttle positioning sensor, still bumping. This bump is actually a hesitation It can be felt in the car best when in drive stopped. at the exhaust the hesitation bump produces a "smoke ring" on a cold morning. It might resemble a "miss" but again no codes. So I replaced the fuel pump and strainer. Still bumping. On first starting, no bumping at engine warms up becomes more and more noticeable..It only happens after the first few minutes of either run time or within the first few miles and gets progressively worse.. when at temp. the hesitation, even though fairly predictable at about 10-20 per minute, is random in the presentation..3 then 1 then 2 then 6 in a row, then1 then 2,ect.. Although it is felt better when in gear, it is not a trans problem as it is plainly noticed in N and P....however it then is central only to the engine..Recently on a trip to Wilmington (about 100 miles) we really noticed how the bump has developed into full blown staggering and stumbling on acceleration when in traffic as well as driving below about 35-40. On the highway, the stumbling /hesitation is not noticeable. even when passing. I hope you can offer a thought..thanks. Dave G.
Submitted: 1 year ago.
Category: Hyundai
Customer: replied 1 year ago.
need to go to bed soon, been waiting just over an hour now. need help.
Customer: replied 1 year ago.
it's 12:00...,going to bed. maybe someone will get back to me sometime tomorrow..I don't get why this seems to take so long. Your experts have 15+ years experience ,,has no one heard of this problem.? I don't mean to sound arrogant, but I'm looking for help and (with your system) often I do not get pertinent answers to questions and I think I'm giving enough information to help get a good direction. I hope you find some good info for me. I'll check back with you in the am. Thank you. Dave G.
Expert:  peterpete190 replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

This "bump" feel may be an issue with the fuel injectors being gummed up slightly causing this fault here.I have seen several fuel injectors become gummed up and cause a restriction with the way the fuel comes out of them/atomizes causing this issue here.If you have not had the injectors cleaned at all this needs done.

If this is done or was done and found o.k. or not the issue here the other issue I have seen is carbon build up on the cylinder head valves mainly the intake valves.If you have not had a carbon clean done with a carbon cleaning machine this needs done.If this has already been done and did not correct the fault here let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
please understand, I'm not a professional, but I do trouble shoot things for a living.I wonder, these factors you mention, would they show a poor performance issues across the driving range ? I have run the "Sea foam" through the intake as well as through the gas tank. I also am pretty good about using fuel injector cleaner about 3X a year. Use dry gas to keep water out of the tank. when I had the pump out the other day, I inspected the tank.VERY clean. Strainer also very clean.easily seen through when held to the light. has over 290,000miles. I was thinking possibilities of the purge valve or evap related stuff.. I can repull the intake and remove and inspect the fuel injectors and repull the plugs and peek into the cylinders..I don't have the money to send it to the dlr.this will take a few days to get to. I'll get back to you. What kind of machine do I need to get carbon out without removing the heads? Dave.
Customer: replied 1 year ago.
I hate that it does not throw a code. seems it would have pre-ignition from the carbon build-up or a misfire or a knock sensor something..
Expert:  peterpete190 replied 1 year ago.

The injectors or carbon build up on the valves can cause this fault here without causing any problems with vehicle operations as it may just be enough to cause the bump feel here at certain speeds or idle.If you clean the injectors regularly there is a chance they are o.k. but I have seen some fail to where they just dont operate properly and one or more need replaced as cleaning will not correct them.

I know some people tend to use a component called Top Engine Cleaner purchased from a parts store or dealer.They run the engine warmed up at idle and remove a vacuum hose (large enough to suck in the cleaner into the engine) and suck in this cleaner slowly while the engine is running.Then once this is done they immediately shut off the vehicle and let it sit for 24 hours then start it up and run it/drive it until the smoke clears (it will cause a smoke screen) and this will clean up the valves fairly good.The other option is most shops have a machine that does the same thing,it injects cleaner into the intake with the engine running to clean the valves and carbon.

I have seen injectors and carbon cause what you have here and in allot of cases not set a fault code or turn on the check engine light.

Thanks Pete

Customer: replied 1 year ago.
Pete, in the mix of originally trying to get an answer, I had been directed to the "leave a deposit "page twice and had to leave 2 deposits before ever hearing from anyone. Being out of 48.00 immediately did not make me happy as I don't have much to work with. So after calling the business line, they refunded my 2 deposits, and said I should be able to ask on the same topic until I solve the problem meaning "accepting an answer". now since I have asked on this prior, am I still able to ask or do I have to pay again,? or do we just call it a day...I still have the problem after warm up. it has been colder lately and has performed much better meaning, after warm up when I would expect it to start "bumping".. It delays doing it and is almost not even noticeable. Then after 15-20 min more driving it starts doing it. Dave.
Expert:  peterpete190 replied 1 year ago.

Unfortunately I am unable to talk about any money here.This is something you would want to speak with customer service on as I do not have any info on any money here.

Were the injectors tested at all or carbon cleaned from the engine at all?

Customer: replied 1 year ago.
no. sadly, asking for help and not doing it shows badly on my part. We use the car every day. Sons car broke down last week 120 miles away, just got it (1990- Honda) back to my house last night. just a bad time to pull all that apart. any other thoughts on this or is this where it ends for you.?
Expert:  peterpete190 replied 1 year ago.

The only thing I can suggest here is to have the injectors tested to see if any need replaced as this can be a common issue for this fault here.If these are all found to be o.k. then I would have the engine checked for any carbon build up needing cleaned to correct this fault.

Let me know if you need anything else and feel free to rate my help as this is how I receive credit for my time here.

Thanks Pete