So I don't have a car to get a work been getting a ride from roomate....
It will be a week tommorw.

I brought in my 1995 max for a new water pump install. It used the old style guide so I had them install the new style guide and tensioner. They said that the timing chain had to come off in order to replace the water pump. They said that it started up fine right after in the install then the next day it didn't.On saturady they said that the spark plugs were fouled and wet with gas. They think this is due to them to forgetting to plug up the air temp sensor. They car started up fine even with the air temp sensor unplugged right after the waterpump/guide install. They mentioned today that it had intermintent spark. About 4 months ago both my crankshaft sensors and my camshaft sensors went bad/dirty. I cleaned them up re-installed and all has been well since then. The car had been running great prior to this incident and the crank/cam sensor issue. My water pump was leaking so this is why I brought it in.

I did find an atricle discussing a similar issue-the mechanic said that they lined the marks up perfectly when they took the chain off and that it hasn't skipped a tooth since the last start up. I think other wise:



"

http://www.asashop.org/autoinc/jan2001/techtips.htm


“Since the problem occurred right after the water pump was replaced, I wondered if the camshaft and crankshaft position sensor signals were out of phase with each other, since the timing chain must be taken off to replace the water pump.”


Vehicle: 1996 Nissan Maxima. VQ30DE
Symptom: Misfires. No spark from the coils for cylinders No. 2 and No. 3. The cam timing is off a tooth.
The problem began with a leaking water pump. After the water pump was replaced, ignition coils No. 2 and No. 3 did not fire.
This Nissan's engine is equipped with a distributorless ignition system (DIS), with a separate power transistor mounted with each one of the six coils. This gives each cylinder one coil and one power transistor. A separate signal from the powertrain control module (PCM) to the base of each of the power transistors turns the power transistors on and off. The power transistors pulse coil negative to ground, based on those signals from the computer.
The technician verified that the signals from the PCM to the base of the power transistors for the other four working cylinders were good. He found no signal from the PCM to the base of the power transistors for cylinders No. 2 and No. 3 at the power transistors. The harness was checked for opens and shorts between the computer and those two coils' power transistors. The signals at the PCM were checked as well. The technician tried running new wires between the PCM and the power transistors, and also tried new coil/power transistor assemblies for those two cylinders, as well as a used PCM. There were still no signals from the PCM to the base of those two power transistors. The camshaft position sensor (phase) and crankshaft position sensor (reference) signals were both scope-checked and had nice, consistent sine wave type patterns with proper amplitude for both signals.
Since the problem occurred right after the water pump was replaced, I wondered if the camshaft and crankshaft position sensor signals were out of phase with each other, since the timing chain must be taken off to replace the water pump. This engine has a main timing chain and two camshaft timing chains. The camshaft timing chains go around the smaller intake and exhaust camshaft sprockets. The main timing chain goes around the crankshaft sprocket, and then up around two larger camshaft sprockets that mount on the end of the intake camshafts, outside of the smaller intake camshaft sprockets that the camshaft timing chains go around. The main timing chain is the one that needs to be removed to replace the water pump.
When I asked the technician to check the engine mechanical cam timing, he found the timing chain was off one tooth. He corrected the cam timing and the two coils started firing once again.
So if you get a couple of coils with no spark and there are no signals to the base of their power transistors, make sure the timing chain is not off a tooth. "

 

I forgot to mention that the engine will crank but won't start. After the waterpump/guide and the chaning being put back on(timing marks lined up)the car started up just fine.

 

bump!

 

The quickest/easiest way to determine camshaft timing is to scope the cam/crank sensors, verifying against a known good. This will only tell you if the bank 2 cam is timed correctly, however generally speaking if you got one out, you got both out.

Have they checked for spark on every cylinder? Really both crank and the cam signals need to be checked, all work needs to be rechecked, including timing.

 

Thank you for your reply.

They said that they swapped out some the cams with some other they had and got a better singal but still not start. They are thinking something is wrong with the computer now, keep in mind I've never had any computer issues no issues when the computer was not showing codes...


Heres some more information.

The said that today the disconnected sensors and the computer is not showing trouble codes for any sensors being disconnected. They said the spark is "very light". I haven't had any issues with the computer I don't see how they could have possibly fried the computer buy just chaning mechanical parts.


So basicly the computer is not throwing any codes with any of the sensors unplugged....

I am going to see if I can locate one from the junk yard. I really just think they friend my computer..... sigh

 

I agree with pmohr here. Don't know what shop told you the chain needs to come off to replace the pump but it seems that harness, sensors, or incorrect timing might be the culprit here.

 

I would say that the timing chain needs to be checked that everything is lined up properly. I'm wondering if the mechanic left the guides or something loose and now the chain has jumped a tooth. A methodical approach has to be taken. Step 1 before step 2 before step 3 -etc. Jumping around from crankshaft sensors to camshaft sensors to air temp sensor to ECU isn't going to get the job done.

 

Well they also said the computer is not throwing any codes even with things like the O2 sensors and cam sensors unplugged but I really do feel that the timing is off/skipped a tooth.Keep in mind prior to this the car ran just fine...

 

Well the air temp sensor was unplugged and I think that's what was causing the engine to get all the extra fuel.

ALso is there anyway to test the computer?

 

Well the new style guide was installed so the new style tension-er would fit, maybe this is why it had to come off.

 

So here are the cliff notes

The car started fine after new guide, water pump and tensinorer install.

They took the chain off and re did the factory timing; said they verified marks lined up.

After sitting for a day the car doesn't start. They say it has light spark.

I feel that the timing has skipped a tooth when they turned it off or it was not lined up properly to begin with.

 

If the timing is off, then the car will not sound the same when cranking as it did before.

Does the crank sound different or more "harsh"?

Check the camsensor, wiring, and harness. This may be the culprit as this had to come off for install. Test for camsensor is a resistance test.

 

You seem to think that the intake air temperature sensor might be the problem. While I don't think that it is, let's check it and find out. Just like the cam sensor, the air temperature sensor can be checked for resistance with an ohmmeter. Also, a bad intake air temperature sensor would give you a check engine light, P0110.

 

Do these jokers still have the car? Is this a dealer or independent shop? Have it towed somewhere else on their dime. I've worked at shops and seen our techs f up someone's car and this happen.

 

The air intake sensor has nothing to do with fuel or anything of the sort. It is only used for onboard diagnostics(fsm) and I can vouch I've gone weeks and month without it hooked up.

Like others have said, I would suspect bad timing or a skipped tooth.

 

So I just got a call about the car. They said that they took the timing cover off and re-verfied the timing and want to show me that it is correct this afternoon so I can look for myself.

They now think its the computer(ECU)since it is not throwing any codes whent hey disconnect a sensor(s).

 

How can I pursue this option?

 

IDK exactly. Call another shop, preferably dealer with a senior tech who knows the VQ, and make arrangements to have it towed there. If they have caused more damage than the original maintenance measures cost, than they should be liable. A good shop will know what you need to do.

 

I will look into this any information about my problem.
IT started up fine after the waterpump/guide/tensioner install but didn't start up the next day. They say the computer is not registering when they disconnect sensors as a test.

 

Take pics and throw it up in the thread. Out of curiousity did the mechanic say he re did all the timing or he did he hand crank the motor back to those markings. If he hand cranked it back to all the timing marks then the timing is for surely off.

 

I should have taken some pics/video.

They had the cover off and showed me that it didn't skip a tooth and it was correct.None of my sensors are connected and the computer is only showing the code P0444. EVAP Purge Control Circuit No Signal .

IT started up just fine last friday and now as of last sat till now it doesn't start. It all looked correct to me. But the computer no showing in codes in mind-bogoling. I'm going to order a used warrantied ECU from the web and if that doesn't fix it I guess I'm out of the maxima family and will be taking the bus. Sadly its' 1.5 hours to work via bus vs 25min drive in a car.

 

Ouch man.

I forgot to mention or ask if the CEL is lit, when you have the key in the "on" position(but with the car not running) If there is no CEL present it usually indicates some kind of malfunction with wiring or a bad ecu.

 

That's garbage, if it breaks in house they should fix it in house. It was driveable when you dropped it off.

 

My CEL is burned out, but the ECM is still not showing any codes.. Any idea on how to find my correct ecu? Mine was build 9/94 in Japan. I only find 5/94 and 12/94. It's fed emission gle.

 

u can prolly find a 96 ECU u can throw in.

 

check for your vitals

 

I want to thank eveyone that contributed there advice about this issue.
I always like to document my car experinces so that other who have similar issues will have something to refer too.

I just got the word thatonce they put everything back together(oil pan acces belts valve cover etc) after re-checking the timing they car started up a few times with no issues. They feel that the no start issue was due to factory security on the car. When I looked the cam/crank all the marks looked correct and the engine rotated with issue.

 

They must not have much experience with maximas if the "security" was the issue. Anyhow, sounds like all should be well now.

 

Indeed, factory security is nothing more than a starter interrupt.

I'd be betting on the timing having been off, and a tech that didn't want to fess up.

 

So was there a need for the ECU still since I see you created a new thread?

 

From what I understand the 95 doesn't have the immobilizer...

They said the car was running at 1pm today, so I will see when I get chance to get there.

 

I don't think so, they didn't mention it in the email. They only mentioned that they think that my security system(factory no NATS) was the issue.

 

So they disabled it completely or did they forget to connect back something that was triggering it?

 

I don't have the details about the resulotion. All I know about the security system is that it will go off if your brake a window rock the car to hard or open the door when it's armed. I have no knowledge on the 95 security system have a function were it can cause a car to not start. I have the original key(no chip) and key fob.

 

There is no glass breakage or motion/tilt sensing feature on the factory alarm. As said, it's a starter interrupt only, meaning if it was cranking, it wasn't the security system.

If you do have the above sensors, either they were added to the factory security system, or you have an aftermarket alarm installed.

 

I see the security system only interups cranking? Well that's good to know. The car was cranking when I was were last week.

 

So I picked up the car today and everything seems normal after driving
back home about 6 miles. I didn't ask what the resolution was just glad to have the car back after waiting so long.