Engine cutting out, backfire on hard acceleration

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desertq45
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Re: Engine cutting out, backfire on hard acceleration (elwesso)

Postby desertq45 » Mon May 14, 2007 6:55 pm

I don't know if I am reading the codes properly... but this is the process I used:

1) pulled the ecu out so I could see the diode and set screw2) made sure the screw was all the way counter clockwise3) started the car4) turned the car off, turned the key on5) turned the screw all the way clockwise until it stopped6) turned the screw counter clockwise about a quarter turn or so until I saw 3 blinks of the diode7) from that point, the diode would blink 5 slow times followed immediately by 5 fast blinks...

I see that as code 55. I could not get any codes with the car running. Is that normal?

So even though the check engine light is on consistenly, it doesn't seem to be storing any codes in the computer.

Other than that... your recap is pretty good. One clarification on the MAFs-- I have the original that I resoldered the connection on (just to be sure), and one I bought on ebay. The ebay unit is in the car now. Neither makes any difference in the symptoms. I read an old thread where I think Tech was discussing the merits of trying several used units in that they can help rule out issues by changing the symptoms. I also read where Jesda bought one for a later model and modified it for a 90. So... I figured what the heck, I'd try that first.

I'm still not convinced the ecu isn't my problem because the when the engine cuts out it is severely abrupt. The tack falls from where ever it is to zero immediately. It is an immediate loss of power even if climbing rapidly in r's when it happens. It seems it will go from 4k to 0k and back again under acceleration. It really acts like all juice to the engine disappears for a split second.

However, it does not affect the HVAC fan or radio or other electronics in the cabin and the battery is a brand new Optima red top.

Throttle position sensor wouldn't cause this would it?


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DrewQ45
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Re: Engine cutting out, backfire on hard acceleration (desertq45)

Postby DrewQ45 » Tue May 15, 2007 1:58 am

desertq45 wrote:Throttle position sensor wouldn't cause this would it?
I had very similar symptoms and having the CAS replaced at T3 resolved it.


Modified by DrewQ45 at 11:47 AM 5/15/2007

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Re: Engine cutting out, backfire on hard acceleration (elwesso)

Postby maxnix » Tue May 15, 2007 3:09 am

elwesso wrote:Honestly I dont thinky ou will get anywhere with infiniti dealership. I doubt IoS despite their volume of G50 parts sales actually knows enough about G50s to diagnose a goofy problem like this.
Greg had to take his to a Senior Tehnician (service manager) to get his bent intake valve diagnosed correctly. Might search for that thread.

Over rich injector and TPS are good areas to investigate also. A power balance test would tell you so much. Greg also knows a good independent shop in Phoenix.

Oh, and you have done the couple of bottles of ISO-HEET?

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Re: Engine cutting out, backfire on hard acceleration (maxnix)

Postby desertq45 » Tue May 15, 2007 4:45 am

maxnix wrote:Greg had to take his to a Senior Tehnician (service manager) to get his bent intake valve diagnosed correctly. Might search for that thread.
Right. He took it to Midway Infiniti. They had it forever trying to diagnose it. He and I had lunch not too long after that. It's tough to find a dealer that really knows much about the G50.
maxnix wrote:Greg also knows a good independent shop in Phoenix.
Probably Scott Haneberger down at Euro Imports. He's a former Infiniti of Scottsdale tech and runs this shop independently. His guys did a couple thousand bucks worth of work for me-- including chain guides. It is always an option, and probably better than IofS... even Joe shrugs when I ask his opinion about the service guys re the Q.
maxnix wrote:Oh, and you have done the couple of bottles of ISO-HEET?
I have not... perhaps I should...

I think I'm going to look into the TPS some more-- it sounds like a good target.

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Re: Engine cutting out, backfire on hard acceleration (maxnix)

Postby elwesso » Tue May 15, 2007 4:46 am

For the record, greg actually didnt have IoS figure it out, he had the car at IoS for a LONG time replacing a bunch of junk and they didnt figure it out!!!

Also, his symptoms were completely different.. Rough idle and always down on power....

Im still sticking to my guns that theres probably only a HANDFUL of people in the entire state that would be able to more efficiently figure this out than yourself. Its easy to cop out and let someone else try and figure it out, but chances are they are going use this as an opportunity to throw parts at the car!

I dont know if TPS would cause these kinds of issues... Certainly a used TPS would be easy to find so you could look into that. hell, greg might have a used TPS for a 90-93.

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Re: Engine cutting out, backfire on hard acceleration (desertq45)

Postby maxnix » Tue May 15, 2007 4:55 am

ISO-HEET is cheap. Try it.

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Re: Engine cutting out, backfire on hard acceleration (DrewQ45)

Postby DrewQ45 » Tue May 15, 2007 5:20 am

I apologize for earlier mistake. T3 actually replaced my CAS (crank angle sensor)... I've edited my earlier post. Thread here...

zerothread?id=144460

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Re: Engine cutting out, backfire on hard acceleration (maxnix)

Postby Q45tech » Tue May 15, 2007 5:33 am

Other than fuel pressure we have been provided with none of the half dozen measurements that one would use [measure] in the first few hours to help reach a diagnosis.

One would data a few WOT runs in rpm segments idle to 2k, 2k-4k, and 4k > redline.

MAF voltage, ignition advance, injection time, rpm, TPS voltage. Battery Voltage during runs. Coolant temp.

One would run these at least twice THEN sit down with a liquid and study the numbers for 10-15 minutes.

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Re: Engine cutting out, backfire on hard acceleration (Q45tech)

Postby desertq45 » Tue May 15, 2007 5:45 am

Yeah... guess that is the difference between a "real" technician and a wannabe/havetabe...

I would need one of those fancy cables and consult software correct?

Is the BlazT cable and software compatible with the Q? I know there are numerous posts about it here, but I don't see it listed on thier website, and just want to be sure. I can use serial connections on my notebook and since it seems much less troublesome than USB, I'm inclined to go that route. Am I on the right track there?

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Re: Engine cutting out, backfire on hard acceleration (Q45tech)

Postby 96Qowner » Tue May 15, 2007 5:55 am

Q45tech wrote:Other than fuel pressure we have been provided with none of the half dozen measurements that one would use [measure] in the first few hours to help reach a diagnosis.

One would data a few WOT runs in rpm segments idle to 2k, 2k-4k, and 4k > redline.

MAF voltage, ignition advance, injection time, rpm, TPS voltage. Battery Voltage during runs. Coolant temp.

One would run these at least twice THEN sit down with a liquid and study the numbers for 10-15 minutes.
And this is why I suggested the Consult. Actually, it sounds like you should get the consult cable and do it yourself - same cost. I'm with Wes and others - this does not sound like a MAF problem. I lived with a bad MAF for over a year, and it was never predictable - not at all like yours.

Something is not keeping up when the rpms and fuel flow get high. So get it on a Consult and do the rpm runs - if you know how to produce the symptoms, you'll see what's going wrong. I'm assuming you're confidant about the fuel filter and the pressure regulator - you measured fuel pressure at the rail, yes? So, it has to be a sensor, which will show up on the Consult. Of course, I'd do that O2 port test for backpressure, first.

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Postby T45 » Tue May 15, 2007 9:47 am

I would check into connections between the harnesses. If it cuts out when you hammer the throttle, it could be because the engine is twisting in the mounts and possibly pulling a connection apart. Either that or there could be a wire that is broken inside the sheathing and has a connection when sitting still but loses the connection when the throttle is applied and the engne moves.

Try a small powerbrake, just enough to make the engne and trans move in thier mounts, and see if it happens. Then jiggle some connectors and wires around.

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Re: (T45)

Postby desertq45 » Tue May 15, 2007 10:59 am

Thanks guys... I appreciate all the pointers!

Since I tried grounding the fuel pump last night, the symptoms have now reverted to the "less able to replicate" type that I originally started with.

The temps are north of 100 degrees in Phx now and I think that has an affect on it. It isn't until the rpms are climbing fast and the vvt is working that it cuts out now and I can't get the check engine light to come on at will any longer.

To recap what I've done:

- Unplugged the harness from the FPCU and ran a ground to the pump via the harness. Ran like it does today.

- Plugged the harness back into the FPCU, no change.

- Unplugged the ECU and then removed it so I could see the diode, then plugged it back in and read the codes (none there).

- Unplugged the ECU, then remounted it and plugged it back in... no change.

So, I have improvement over yesterday morning... but I think it is still just the flakey symptoms of whatever is wrong.

I think I'll call Joe and have him send me some new plugs (eliminate another variable).

Also, Wes (or anyone), did you see my question about the consult cable and software?

Thanks.

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Re: (desertq45)

Postby desertq45 » Wed May 16, 2007 6:22 pm

Ok guys... thanks to all who chimed in... I finally think I've nailed this problem.

This morning I got in the car to drive to the office and it was 80 degrees outside. I hadn't driven the car in about 14 hours so it had a chance to cool down to the ambient temp.

As I applied throttle, the car bucked hard. I tried holding it at 2000 rpm... it cut in and out eratically. The check engine light came on and stayed on and I limped the car the rest of the way to work. As I thought about it through the morning it seemed that if it was bucking worse when cold, and ran better when hot... it had to be electrical. That thermal dynamics thing... the connection expanding when hot and making better contact.

I also figured I'd ruled out fuel delivery and the MAF, didn't really think it was TPS by the way it was bucking... so I was leaning heavily to Crank Position Sensor. I called Joe-- $433... ouch. So I decided to clean the harnesses to the CPS and check the computer one more time for codes.

I actually did it in reverse order and I'll be darned if there wasn't a code 11 in the ECU... Crank Position Sensor.

Out cam the dremel and the dielectric grease.

The main connector had a fair amount of white corrosion on it, but not excessive, but when I was done it was gleaming copper. I buttoned up the engine and went for a drive.

Problem gone. No bucking, no stuttering... nothing but strong G50 acceleration!

Sure is nice to have this one behind me... from now on, I'll check EVERY connection.

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Re: (desertq45)

Postby 3Q Jay » Wed May 16, 2007 7:10 pm

and so much more satisfying to fix it yourself! good show.texasoil swears by stabilant-22. i now use it religiously.

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Re: (desertq45)

Postby maxnix » Thu May 17, 2007 2:49 am

Great news. Those connectors can cause a myriad of symptoms.

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Re: Engine cutting out, backfire on hard acceleration (desertq45)

Postby goody90q45 » Thu May 17, 2007 3:06 am

desertq45 wrote:Is the BlazT cable and software compatible with the Q? .......I can use serial connections on my notebook and since it seems much less troublesome than USB, I'm inclined to go that route. Am I on the right track there?
Congrats on the DIY fix of your Q. As you said, check all the connectors for corrosion. If one connector was corroded chances are they all have some level of corrosion. I had a similar problem with a 90Q that i bought and cleaning the connections made a huge difference.

As far as the consult cable, I have the Blazt setup for my Q but the first cable I was sent had an older chipset (CP210X, same as the NICO group buy) and it would not connect to the ECU. Jason Dear at Blazt sent me a newer cable with an upgraded MDTI chipset and it works great. If you place an order make sure to request this newer chipset. The Blazt package is nice because you can order NissanDataScan from them at the same time. Good luck.

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Re: Engine cutting out, backfire on hard acceleration (goody94q45)

Postby elwesso » Thu May 17, 2007 7:20 am

Very NICE!! Its frustrating and satisfying at the same time when it turns out to be something simple!

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Re: Engine cutting out, backfire on hard acceleration (elwesso)

Postby desertq45 » Thu May 17, 2007 7:32 am

elwesso wrote:Very NICE!! Its frustrating and satisfying at the same time when it turns out to be something simple!
Yeah, you said it. I cleaned all the connectors while I had the plenum off, but obviously missed this one. The darn things get so brittle that when you go to pull them apart the "spring" lock breaks half the time. That is what happened with the secondary CPS when I cleaned it... and I had to wire tie it in place. I still don't know how I missed the main connection next to the airbox... but it was the the problem. Getting the code to stick also helped...
goody94q45 wrote:As far as the consult cable, I have the Blazt setup for my Q but the first cable I was sent had an older chipset (CP210X, same as the NICO group buy) and it would not connect to the ECU. Jason Dear at Blazt sent me a newer cable with an upgraded MDTI chipset and it works great. If you place an order make sure to request this newer chipset. The Blazt package is nice because you can order NissanDataScan from them at the same time. Good luck.
Thanks for the response to the Blazt... I'll make sure I get the newer chipset. Do you suggest calling Jason directly?

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Re: Engine cutting out, backfire on hard acceleration (desertq45)

Postby goody90q45 » Thu May 17, 2007 7:52 am

desertq45 wrote:Thanks for the response to the Blazt... I'll make sure I get the newer chipset. Do you suggest calling Jason directly?
They're in New Zealand so phone calls are out. I can tell you that Blazt customer service was great and Jason never kept me waiting more that a few hours for a response to my emails. Also, shipping from NZ only took 4 days which is quicker than the domestic shippers.

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Re: Engine cutting out, backfire on hard acceleration

Postby Markote23 » Sat Oct 06, 2018 4:50 pm

My 06 Titan has a stall/ backfire issue when cold. It will do it 2-3 times and then runs fine. No codes. I read a similar post and checked Flywheel bolts which was his solution. 3 months ago this started after Crankshaft Positioning sensor went bad. I did change the camshaft sensor at the same time. The intermittent part confuses me, because it runs perfect after the 2-3 stalls and only when it’s been sitting for a period of time.
I live in Mesa, Az. And have seen a lot of reference to infinity of Scottsdale. I’m to the point of having it diagnosed, where would be a reputable shop be?


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