How can you tell when it's no longer work? Will the power be off due to incorrect timing reading? Will the SES's light turns on?

I am suspicious that mine may be malfunction because of my recent dyno readings. With all the mods that I have on, the car dyno at best 189 hp/211 tq on the DynoJet248C (SAE correct). I compared mine to another member who had his done (w/similar mods) and his was about 20 hp/tq higher. The operator told me that my timing was off...perhaps due to the UDP's. I don't think this is the case since the VQ3.5 is internally balance w/no timing mark on the pulley. Any inputs guys?

-Vince

 

You might be able to tell from the dyno withOUT too much smoothing factor. Or an OBD scan/log could compare timing.

You running 91-octane or higher? What brand?

 

first time was 93-Amocco's & the second time was 94-Sunocco's

 

My next step would be to do a pull and data log on the OBDII port. I'm pretty sure you can't directly read knock counts, most OBDII ECUs won't but it may be different for each manufacturer and I've never logged a Nissan ECU even though I have a logger. What you *can* tell from a log would be timing. If you see it get yanked, the culprit is almost always knock.

If you do have excessive counts but you don't hear pinging, you may have phantom knock (something else causing enough of a vibration to make the knock sensor trigger) OR it could be a bad sensor that's not throwing a code but is sending knock triggers.

How did the tech know timing was off? Do you have a timing profile?

 

He said that the power curve has a lot of spike in it.
The power curve of both dynos when overlaid (mine vs. the other) were almost identical but mine was off by 20 hps/tqs. I will post the graph if someone will host it for me.

 

bump...more inputs? C'on anyone?

 

YOU WILL KNOW IF ITS BAD
I had the sensor recall done and the stealership put in a sensor that was bad. I pulled out of the stealership and almost got hit, the car would not go over 2600 rpm's it would choke, gasp and searge. Then the ses light came on.
So you will know if its bad, you dont need a dyno.

 

Are you talking about crank sensor?

 

Sorry VMaximus02, just rememered I owed you the Dyno chart. Well, here it is...

Following is VMaximus02 description of this chart:

"Here is the scan of the 1st dyno-run. The top curve is from another car w/almost the same mods. The differences between the two car are his has the Frankcar AI's, Warpspeed's Y-pipe & B-pipe w/17" GLE wheels (mine is 16" GXE wheels).

 

This is why before and after dynos are important, but I agree that the numbers are low. Yeah, there "could" be a problem on your car. But it could be literally anything. Here's where an OBD-II scanner/datalogger comes in handy.

Somebody else had an issue with a 2k2 dynoing low awhile back. Read back a few pages. I think it was ToYLeT but I'm not sure. IIRC he got the problem fixed but I have no idea what it was.

My brain is fried from studying. One last final....

 

I feel you regarding finals...am studying my *ss off right now!

The car feels very strong and seems to pull very smoothly. The first dyno run (which was posted) was before the crankcase sensor recall and a ECU flash, plus I'd since changed 4 of the 6-sparkplugs...the last 2 @ the firewall was a pain to remove so I haven't done it. (FYI: When I first brought the car for hestitation TSB, they replaced the MAF but didn't flashed the ECU because they said they couldn't do it). The second dyno was done because I told the owner that my number was low compared to one of the previously dyno's car and requested for a re-dyno since their computer system kept crashing during the dyno session. He agreed for a re-dyno but told me that I have to pay for it if the number doesn't change. The first re-dyno, the computer registered 179hp. The tech called it a scratch. The secondth & thirdth dynos registered closer the first dyno run (lesser hp but slightly higher tq reading). This was when I became suspicious because I saw the tech did some calculations while he enter some figures to the dyno's program. I wonder if the tech can manipulate the dyno run to read similar to the first run so they can get paid? Honestly, the car is run very strong and I am doubting that my second dyno was accurately done. I had cashed out $175 for both runs and I have no more $$ to do another.
Anyway, what do you think about the situation?

 

Vince -

Sorry that the re-dyno didn't work out for you. Do you remember the name of the tech? The guy who was there on both of my visits was name "Weet" (sp?). I talked to him about cars for a while in between runs and he seemed knowledgable and helpful, offering to check/clean my MAF to see if that fixed the lean condition. He just didn't seem like the kind of guy that would intentionally cheat you out of your money. On the other hand, I don't know him from Adamd and he could just be doing what the boss told him. I guess I'm giving them the benefit of the doubt.

I just cleaned my MAF myself and plan to redyno again soon. I may have my dealership do a complete diagnosis on ConsultII or just buy a scanner (although I'm not sure a scanner can tell you if a sensor is bad).

Anyway, you're in Dulles and I'm in Herndon. I'll post if/when I figure out why I'm so lean and if we both could find the time, we could do a couple pulls from a roll. IIRC, our mods are almost identical so if both rides are healthy, we should be neck n neck.

Later,
John

 

Thanks John,

The first guy was Eric (young guy probably in his early 20's), not Adam. The second guy has blond hair with a pony tail...not sure of his name. He seems much more knowledgeable than Eric and suggested that my timing might be off due to the UDP's. When I told him that the UDPs might not be the cause of the problem because our engine is internally balance, without a timing marks as of the previous VQ's generation. He then said that the timing can be off due to the crankcase sensor because the computer is reading from it...which I told him that I had recently done a recall on that sensor. He was baffled 'cause he didn't know much about this particular engine and suggested that I should have someone check the timing mark while the car is at WOT's and compare the results to other "healthy" engine.

I used to live in Herndon but now in Sterling, right across from the Herndon police station. Your suggestion of doing a couple of pulls for comparison is a great idea. However, the question would be where 'cause the police around here are very ****...since they are actually doing their job of policing the area!

Good luck with the re-dyno! Hopefully your leaning issue is resolved with the MAF's cleaning. FYI, my car used to run lean about a week or two after installed the Injen CAI intake. I had my fuel system cleaned w/B&G44k hooking up onto the vacuum hose near the throttle body while the engine was running for about 1/2 until the can was empty. Then the MAF's and the throttle body were cleaned. Afterward, another bottle of B&G44k was poured into the gas tank. These procedures completely cured the knocking/pinging issue. My air/fuel ratio reading on all of the dyno runs was averaged at 13.2-13.5.

-Vince