90 maxima big hesitation and gas eater Plese Help
90 maxima big hesitation and gas eater Plese Help
My sister's maxima has a big hesitation when you take off from a stop. Also when you are cruising at 45 mph is sounds like it's breaking up. But you get on it it's fine or get past 45 mph it's good. From a stop as it goes 1st gear fine and though 2nd and 3rd gear the car surges. The has a full tune up plugs,wires,cap,and rotor fuel/air filter timing belt, all new injectors and O2 sensor. the fuel pressure was good. I opened the EGR with my fingers and the car breaks up at idle. So i guess it's not clogged. It opens when you rev it up on the rev. the car is eating so much gas to. Thanks
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mtcookson
- Posts: 2204
- Joined: Thu Nov 21, 2002 12:43 pm
- Car: 1991 Nissan 300ZX
1992 Iinfiniti Q45
and much much more - Contact:
I would check the ECU codes to see if there are any error codes stored.
Since its had a good tuneup, other things I would check would be the throttle position sensor and I would check for vacuum leaks as well just to be for sure. Possibly the coolant temp sensor... but not too likely. Another thing to check would be the MAF as well.
Does the engine feel like it is bogging or completely cutting out, as you described by "breaking up". Generally a bogging occurs when there is too much fuel causing a rich mixture and cutting out occurs when there is too little fuel causing it to lean out. It doesn't sound like a very big difference but once you've experienced a rich cut out and a lean cut out you can definitely tell a difference.
Since its had a good tuneup, other things I would check would be the throttle position sensor and I would check for vacuum leaks as well just to be for sure. Possibly the coolant temp sensor... but not too likely. Another thing to check would be the MAF as well.
Does the engine feel like it is bogging or completely cutting out, as you described by "breaking up". Generally a bogging occurs when there is too much fuel causing a rich mixture and cutting out occurs when there is too little fuel causing it to lean out. It doesn't sound like a very big difference but once you've experienced a rich cut out and a lean cut out you can definitely tell a difference.
Re: (mtcookson)
OK, I am going to check for codes. The car has all new vacuum hoses when the injectors were done. But I'll go over them. The was getting 165 miles to a tank. I just did the exhaust manifolds and the O2 yesterday. I spoke to my sister today she can tell all ready the gas mileage went up. So I'll see how it does. But still bogging like crazy. I will check sensors. Thank you, Marcus
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mtcookson
- Posts: 2204
- Joined: Thu Nov 21, 2002 12:43 pm
- Car: 1991 Nissan 300ZX
1992 Iinfiniti Q45
and much much more - Contact:
Ahhh, if its bogging then that is most likely a rich condition which is either too much fuel or too little air basically. MAF issues will definitely make it run rich as will the coolant temp sensor (the on with the square yellow plug).
Were the injectors you got new or rebuilt? May get a long screw driver (or automotive stethoscope) and put it on each injector to make sure they're pulsing evenly and not sticking. When you checked the fuel pressure, was that while the car was running? If so, you may check the fuel pressure after the system has been primed to make sure pressure is not bleeding off. It could be possible that fuel could be leaking past one or more of the injector o-rings.
Were the injectors you got new or rebuilt? May get a long screw driver (or automotive stethoscope) and put it on each injector to make sure they're pulsing evenly and not sticking. When you checked the fuel pressure, was that while the car was running? If so, you may check the fuel pressure after the system has been primed to make sure pressure is not bleeding off. It could be possible that fuel could be leaking past one or more of the injector o-rings.