I recently purchased a 2008 EX35. After driving it for about a month it began to stall on cold starts and I noticed the acceleration was weak and gas mileage was poor(9mpg in city/hwy driving). When the engine is cold the car always stalls on the first start, but starts right up on the second try. When the engine is warmed up the car doesnt stall, but still has problems accelerating and poor gas mileage. It has been getting progressively worse, and actually stalled on the first two tries today.
I have taken it to three mechanics, but none of them had an answer. One did suggest a bad fuel pump/filter, but wasn't sure. From my research this might explain the stalling issue and possibly the acceleration issue, but not the poor gas mileage. I am located overseas, and the local Infiniti dealership refuses to work on US spec cars so that is not an option. Would really love to hear any suggestions anyone has. Could the fuel pump be causing all of these issues, or is more than one problem?
Stall on cold start, poor acceleration/gas mileage
Re: Stall on cold start, poor acceleration/gas mileage
Thanks XIS. Guess I should have mentioned in my post, I did a search before I posted and read all those threads. Those issues were related to intermittent or warm/hot engine or in motion stalls. My problem is specific to cold starts only, which is why I started this thread. I do think my issue could be the fuel pump like it was for some others, but the poor gas mileage is throwing me off.
Re: Stall on cold start, poor acceleration/gas mileage
What octane of gas do you use overseas?
Re: Stall on cold start, poor acceleration/gas mileage
93. The highest available in my area. The previous owner used the same and didnt have these issues.
Re: Stall on cold start, poor acceleration/gas mileage
When did you buy the car and how many miles on it?
Since it is a used car, I will reset the ECU by removing the negative battery cable and leave it for 15mins to half hour. ( you'll lose your auto up driver windows setting and possibly some radio setting which is an easy fix)
- if problem exist. I would check the fuel pump. Does it make noise when you shut the engine? (humming sound under rear passenger seat. There is a TSb for that specially the 2008 model. Mine was replaced twice. The 9MPG you are getting is a hint the fuel pump might be the issue. I would like you to observe (dash screen) how accurate the fuel left in the tank vs how many miles to empty. When you reach 50MIles to empty, see how fast this number goes down even if only driving 5-8 miles. My second bad fuel pump gave me a reading of 50miles left in the tank so I drove it for another3 miles and quickly went down to 25miles. But I never had stalling issue and poor performance even with bad fuel pump...???
Reset the ecu then pls. Report back.. Check also any lose vacum hoses and bad PCV valve....
Since it is a used car, I will reset the ECU by removing the negative battery cable and leave it for 15mins to half hour. ( you'll lose your auto up driver windows setting and possibly some radio setting which is an easy fix)
- if problem exist. I would check the fuel pump. Does it make noise when you shut the engine? (humming sound under rear passenger seat. There is a TSb for that specially the 2008 model. Mine was replaced twice. The 9MPG you are getting is a hint the fuel pump might be the issue. I would like you to observe (dash screen) how accurate the fuel left in the tank vs how many miles to empty. When you reach 50MIles to empty, see how fast this number goes down even if only driving 5-8 miles. My second bad fuel pump gave me a reading of 50miles left in the tank so I drove it for another3 miles and quickly went down to 25miles. But I never had stalling issue and poor performance even with bad fuel pump...???
Reset the ecu then pls. Report back.. Check also any lose vacum hoses and bad PCV valve....
Re: Stall on cold start, poor acceleration/gas mileage
Thanks for the suggestions AWGD8. I just bought the car a few months back. It has 47,000 miles on it. I also had a major problem with the steering column, and had the entire upper steering column replaced. When this work was done the battery was unhooked, resetting the ECU. I also followed the directions in the service manual to do the throttle pedal release & idle air learning. This seemed to help for a short while immediately after, but the problems were back the next time I drove the car.
I did have the experience of the mileage range readout dropping rapidly on a low tank. It actually went from 21 miles to blinking lines(zero) in about 3 miles. I have had multiple mechanics look at it and none found any loose vacuum hoses. Based on everything I have read, my limited knowledge, and suggestions from others I have decided to go ahead and have the fuel pump replaced. I know for a fact it was not replaced under warranty, and so it is very likely the issue, or at least one of the issues. Should have that done tomorrow, and will report back once it's done.
I did have the experience of the mileage range readout dropping rapidly on a low tank. It actually went from 21 miles to blinking lines(zero) in about 3 miles. I have had multiple mechanics look at it and none found any loose vacuum hoses. Based on everything I have read, my limited knowledge, and suggestions from others I have decided to go ahead and have the fuel pump replaced. I know for a fact it was not replaced under warranty, and so it is very likely the issue, or at least one of the issues. Should have that done tomorrow, and will report back once it's done.
Re: Stall on cold start, poor acceleration/gas mileage
Just picked the car up from the shop. Car started up cold with no hesitation on the first try. It's accelerating smoothly and mpg is back to normal. Looks like all my issues were related to a bad fuel pump. Thanks again AWGD8 for the advice. Now I can finally enjoy my new ride!