Hey, I have a 99 SE with about 71k on it. About 3 months ago the car started running like ****, so I took it to the dealer. They checked everything out and came to the conclusion that coil #6 was no good. They replaced that, but some of the hesitation still remains ~1.5k. It is MUCH better than it was, but now under hard acceleration I get a backfire from the intake. I've heard that it could be the cat, but i'm not sure, as the power still seems to be there. Does anybody know the testing procedures for the coils? Anybody else have any experience with this?

Thanks,

Lamar

edit: What is the recommended service manual and where can I find it?

 

Google is your friend...."Nissan Maxima Factory Service Manual"

I've never heard of 'intake backfire'. I couldnt even imagine what it would sound like. If one coil pack was bad, its possible another may be.

 

Quite possible. Anybody know the testing procedures? I can't wait for the service manual. We use Mitchell at my work, but they don't list the specs for the Maxima's coils.

On a side note, I've read somwhere that Mitsubishi makes coils that are compatible. Does anybody have part #'s or website where I could pick these up?

Thanks Again.

 

I've seen "intake backfire" first hand, I know it exists, not for a Maxima though. It was a 90 Pontiac Grand Am with TBI (Throttle Body Injection). I got scared sh.tless first time I saw it, it sounds like a big BOOM. You don't want your face anywhere near the throttle body, believe me!!!

 

Bump........

What are the specs for testing the coils?

 

To check the coils you measure their resistance. Unfortunatally I don't know the exact resistance they should have, we need somebody with search access to answer this.

On the otherhand if you have a coil that is not firing you should probably pull your engine codes and you'll see a misfire code. They generally even tell which cylinder is misfiring. Then swap the coil with another cylinder, clear the codes and see if you start getting a missfire on the other cylinder.

You need to be careful though and try to avoid backfires as it can ruin your MAS (mass airflow sensor) and they aren't cheap.

I could be wrong, but I don't think a bad coil would cause a backfire though. From what I've read intake backfires are generally caused by timing issues.

Let us know what you find.

 

Hey, I just found this page from the FSM with coil testing procedures although I'm not sure what year of FSM. It's easiest to view if you save it then open it as an image so you can zoom.

http://kcmaximas.org/tech/FSM/EC-122.jpg

 

Thanks for the help. I guess I forgot to mention that there are no codes present. The only time that I've thrown a code was when the 1st batch of coils went back about 30k ago. It was for a random misfire. The ECU never narrowed it down to a specific cylinder. I do still have a "stumble" at idle (misfire imo).

 

Are you having this while the car is running?

I had this situation when I put in my new used motor, the car wouldn't start and when you crank the motor over, there was flames from the intake. I was getting backfire through my intake because my timing is off, my car had pre-ignitiing and the intake valves are opening at the same time hence flames are traveling up the intake track. I was told that basically the connection of the block and the tranny was not good, it wasn't metal on metal, (crude and dirt and rust) was build up on the motor side hence causing a bad ground for the motor. This also cause the CPS voltage to jump radically therefore causing the backfire. I resurfaced both surfaces of the engine and tranny and that fixed the problem.

I dunno if that is the reason why you are backfiring but I think that it is definately timing/ignition related. Check your coil, plugs, cps. also the service manager of the dealership said that checking the grounds motor (ie block, altenator...) may also be a factor to the problem, so resurface those first before taking off the trans.

 

AFAIK the tranny has never been removed from the block, but I will look in to that. The backfire is intermittnet. It happens once in a blue whenever I'm getting on it in 1st and 2nd. Timing chains aren't known to skip teeth like some belts do are they? I do have a rough idle though, so the timing may be an issue.

 

I think your right it's a timing problem due to a wiring and/or ground problem.

When I read your description I remembered a simular problem I was having a few years ago with my step daughters 85 Monte Carlo SS. It started running really poorly, stumbling, and backfiring. I checked the grounds I could find, tried setting the timing, new plug wires, new distributor cap, eventually a new distributor. Sometimes I thought I had it solved and after putting on a new part it would run fine for a few blocks then stumble, nearly die, and backfire. I finally gave up and took the car to the shop the mechanic put it on the scope and saw that it would fire continiously until the ignition module overheated then it wouldn't fire until the module cooled then it would repeat the cycle. He also found the problem was a ground from the firewall the the back of the block was loose so when it had a good contact it ran fine when it lost its contact it ran terrible. Once he cleaned the contacts and tightened the connections everything was fine. I still don't understand why the block needed more than one gound, the negative cable was nearly new and was grounded to the frame and the block.

Sorry for the long story. Check the service manual and verify all the grounds are clean and tight.

 

I had it happen on my car when my battery was dying. It sounded like someone was shooting a gun under my hood.

 

Bad MAF??

 

It may cause rough idle but I don't think its bad enough to cause backfire. If you are checking the grounds, check the block (above the tranny, under the intake box, and above the alternator) Best thing to do is if you want to spend the money, when it is doing that, take it to the dealership right away. They do have the available equipment and the know how to check timing, voltage on sensors, even though they charge an arm and a leg... good luck.