93 maxima gxe drives sluggish after warms up

[dustye]

When you start the car the fuel pump humms. I just changed the fuel filter and it has new plugs and wires. The pump even humms after I turn it off. It drives fine until it warms up, then the idle starts to bounce and it drives sluggish until it picks up then drives ok until I stop again or I really have to get on it. What could the problem be. Any ideas will help out a bunch.

[Nahkapohjola]

Originally Posted by dustye

...The pump even humms after I turn it off. ....

U have to test fuel pressure; maybe regulator is leaking?

Replace distr cap. ... And then some; read all pages from link below

[dustye]

so should I change the cap and just go ahead and change the regulator also.

[dustye]

so I should change the cap and would it hurt for me to just go ahead and change the regulator.

[Nahkapohjola]

If possible, its good to pinpoint the cause first. Fuel pressure 'is formed' by electronics control (wiring/connectors/ECU), then the pump, then hosing and lastly regulated with the mechanical pressure regulator. Each may have 'its' problems. The gas related tar-residue also may form blocks /jam nozzles... (there 'sea-foam' cleaning fluids may help).

[dustye]

I was talking to my mechanic friend about my problem and I completly overlooked the exhaust leak, and how it actually came about. I didn't pay attention that when it started acting up is the same time I got the exhaust leak. He told me that my cataylic converter was probably clogged and it built up pressure that caused the probably cracked my manifold causing the exhaust leak. Does anyone agree or disagree with this theory.

[Nahkapohjola]

Exhaust leak before O2 sensor interferes with oxygen content measurement; this is used in adjusting injection and one cause to bad performance. First issue is to locate and correct all leaks. Healthy piping will never leak - even if you weld the cat closed ...(Manifold studs tend to break, laborous job to correct).

I dont think cat is the problem cause, however its a good point to charge customers... Any piping causes back pressure, with or without catalyzator; however it can also be clogged. Wait and see, first repair leaks.

"...It drives fine until it warms up, then the idle starts to bounce and it drives sluggish until..."
1. O2 measurement 'works' only after warmup,
2. Cold engine /ECU uses TPS, runs without O2 feedback.
1+2 = exhaust pressure is there always when engine is rotatin.
4. O2 is NOT idle related.

Leak has 'no link' with fuel pump problem.

[dustye]

I have done everything to this freakin car, I fixed the exhaust leak and changed the cat but it still boggs out now even worse then it did before. Does anyone have any ideas please help I am getting ready to blow this car up.

[Nahkapohjola]

Originally Posted by dustye

I have done everything to this freakin car, ...

What does "everything" consist of? Check out which issues - on the link below - have been addressed and pls tell; theres some 24 pages...

[dustye]

I went to the link and the only thing I could see that could even relate to my problem would be a leak in one of the hoses to the egr or the surge tank. But would that cause the car to have an exhaust leak? That is the only thing that doesn't make sense. I have changed the cat which would be the most common reason on why the car would bogg out after warming up and could cause the exhaust leak.

[dustye]

one more thing could it be the o2 sensor. I don't think so cause that is just the mixture of gas and air right.

[Nahkapohjola]

Originally Posted by dustye

I went to the link and the only thing I could see ....

In maxima its 'all about' electronics, take a new look. Measure Charge voltage? Swap new plugs, wires, cap ... add/clean grounding wire to distributor as suggested. Read again why... Connector & gnd cleanup takes 16 hours.

Self diag tells O2 sensor status. Exhaust leak is exhaust leak: 'no connection' to sensor condition - except pipe leak affects gas composition, warping O2 signal measurement. Go and tst all signals, page 9.

When cold, O2 is NOT used. Only TPS and MAF. ... After warmup, TPS 'is not used' only MAF and O2. .... If you havent yet repaired exhaust leak, not much hope getting maxima fixed? Next try swap MAF and O2 sensors; (note: first three reman MAF's will likely be DOA.)