Hey Dan,

You helped me out with the o2 sensor problem so I figured that maybe you could help my buddy out with his problem. Here goes:
He has a 96 se and he just got an engine swap and got a 99se engine with about 1000 miles put into his car. Now before his car was really fast and it would just blow me away but after the swap the car is a little sluggish. Actually a lot sluggish. He also had a new transmission installed as well.

You have any ideas on why that is? I thought that maybe it just needs some break in time because it is still new and also that the engine had been sitting a while, like a couple of months. I also thought that maybe he should have the spark plugs changed just in case. My buddy also thought that the "PCV" may have a problem and that the car just isn't breathing right.

Also it is common knowledge that the 96 is one of the fastest of the max's because of the exhaust restrictions. Would the two engines be that different? It just seems that the car is really sluggish in the low end and then it starts to pick up but not like his old engine. Just thought that maybe you would have some ideas.

Thanks in advance,
Jason

 

You have described a problem but not provided many clues.

The Positive Crankcase Ventilation valve is not to blame. If the PCV valve were stuck open you would have a rough idle. If it were stuck closed you'd have oil leaks. The PCV (good or bad) isn't a performance-limiting part. The engine doesn't "breathe" through the PCV.

The two engines are the same.

No, the engine doesn't need more break-in time.

In the absence of more specific symptoms I have to suspect that something was overlooked during installation of the new powertrain.

You have to distinguish between an engine problem and a transmission problem. Sluggish could mean the engine isn't developing enough power. Sluggish could also mean the transmission is in the wrong gear. Either condition makes a car sluggish but the remedies are quite different.

 

A lot of $$$, or what?

 

In the absence of more specific symptoms I have to suspect that something was overlooked during installation of the new powertrain.

You have to distinguish between an engine problem and a transmission problem. Sluggish could mean the engine isn't developing enough power. Sluggish could also mean the transmission is in the wrong gear. Either condition makes a car sluggish but the remedies are quite different. [/B][/QUOTE]

Thanks again Daniel for giving a quick response.

Well I talk to my buddy this morning and had him read your response and he is sure that it is a engine problem, not a transmission problem. We were thinking about what you said about something being overlooked and he told me to ask you what your thoughts are on the posibility that the ???wendage tray??? may have not been re-installed (spelling)?
Would the absence of this part cause similar problems?

Well I don't know what ask to ask except what things could these two maxima loving yet amateur mechanics look for in the driving as well as any visible signs in the engine that we could look for.

Also it seems that the most difference is in the low end power...not so much in the high end. Are there components that are mostly used during these rpm's that would not affect the performance so much in the higher rpm's?

I know there are a lot of questions, but my buddy is freakin' out because this was suppose to not neccessarily be an upgrade in performance but just more reliability and the same performance. Thanks again Daniel.

 

Well actually not as expensive as you would think. Just be sure you find a guy who has an engine that was out of his car that was totaled (hit from the rear ) and is just trying to salvage some money out of his car. And also if you have an associate that is a mechanic and will give you a discount on labor. Hey I know that is a lot of if's, but hey it could happen, again.

 

The 4Gen Maxima engine does not have a windage tray.

This probably means you don't have ...
- inadequate fuel pressure
- obstructed intake
- obstructed exhaust
... and that's encouraging.

Does the engine start readily?
Does it idle smoothly?
When accelerating, is the engine power smooth?
Is there any color to the exhaust gas? Any odor?
Any signs of dragging brakes (hot rotors after driving)?

Most engine parts contribute to good operation at all RPMs. One thing comes to mind: a bad torque converter is most noticeable at low engine and vehicle speed.

In the absence of clear trouble symptoms you have to fall back on basic principles. Make a basic diagnostic evaluation including ...
- a careful visual examination of the engine compartment wiring, vacuum hoses, and throttle cables
- a careful visual examination of the exhaust system (look for a crushed pipe)
- a compression test
- an intake manifold vacuum test
- a fuel pressure test
- an exhaust back-pressure test

This will take time and patience. There is no short cut.

 

At this page:
http://www.autozone.com/Library/HowT...ertertest.html
I found this information:

If the vehicle lacks power when it is pulling away from a stop or when passing, it has a plugged catalytic converter or the torque converter's one-way stator clutch is slipping. To determine which of these problems is causing the power loss, test for a restricted exhaust on the engine. If there is no evidence of a restricted exhaust, the torque converter's stator clutch is slipping and not allowing any torque multiplication to take place in the converter. To repair this problem, the torque converter should be replaced.

Does this description match your idea of "sluggish"?

 

THANK YOU DAN.....

YOU ARE AWESOME!!!!!!

We will try to do some of those suggestions this weekend...I'll try to keep you posted. Thanks again, you are a great asset to this forum.

Thanks Buddy,
Jason

 

Well his main idea of sluggish is that the engine seems to struggle at the start and continues until he reaches about 3000 rpms....and also it just isn't the same type of ride as his 96. He does have a 5sp and I thought that manual transmissions didn't have torque converters.

And to answer your questions: the car does idle smoothly and actually the car starts more readily then his 96 did. The poswer is smooth but just struggling at the beginning. No exhaust odor or color but we are going to check over the car really slowly on saturday like you suggested and see if we can get to the bottom of the problem. Another friend of ours used to be a mechanic so maybe he can track down some of the parts to do the tests that you mentioned.

Thanks again

 

Just out of curiosity, why did u do the engine swap? Did your old one go bad or something? HOw many miles were on it?

 

That's right. I wrongly assumed his Maxima has an automatic. Something less than 10% of Maximas are sold with the 5-speed.

 

No biggie, it was my fault I should have been more clear.