knock sensors.. no solution

[alexander]

Had the new KS's and harness's installed with a sh...t load of new hoses and the hestitation on acceleration is still there.Only happens when Q has been on the go for over 20 minutes.Oh well. Something else must be triggering the timing to retard.Very frustrating the last two years.

[Infinitiguy19]

Have you verified with a Consult that the timing is indeed retarded when the engine is fully warmed up?

Does it do it at 20 MIN on the dot or just ever time the engine is fully warmed up?

Have you followed this procedure:

[Q45tech]

The ecu retards ignition advance based on coolant temperature. I starts above 194.9F [as read with Consult] and decreases 1.0 degree per 5 F increment. Ihis does not show up in the base timing at idle .

This is part of summer overheat protection by 215F a total of 5 degrees has been removed.

Best to data log various rates of accceleration [throttle position = TPS voltage] to see effects.

The point is to make sure cooling system is as brand new. Rad, coolant, fans as every year from brand new the cooling capacity declines from reduced air flow [dirt and fin corrosion].

More than 50/50 AF will reduce the cooling system capacity.

Defective fuel will fire the KS system as the coolant warms up from increased sub audible knock. Again the only way this can be tracked down is to datalog ignition advance against a KNOWN reference acceleration.

[maxnix]

Hope they did a heck of a lot of cleaning of plenum. lower runners and rings for the gaskets between to as new spotless condition. Getting all the muck out of the top of the V will help later diagnosis.

EGR valve and tube, IAC valve, and TB should also be done.

I still wonder if a trip to San Diego wouldn't be a better solution to these guys sucking your pockets dry.

[alexander]

The last test drive done by senior Infiniti tech(1989) had the Consult pop the KS codes and the instant the timing retarded.Coolant is all new as is fan when the welch plugs were replaced last year.The first 15 minutes or so in the morning, the Q accelerates great. When totaled warmed up, it still chugs up the Sf hills, even WOT can't get much speed up the steepest hills.my '91 Q would fly up the big hills when trying to clear out the injectors on WOT.

[Infinitiguy19]

With all that maintenance why don't they guarantee there work?

They should have this problem fixed a long time ago if they are the dealership, Because they supposedly have access to tools and people with lots of knowledge on the G50.

Seriously you have OVERSPENT on this car.

I would defiantly check the above picture and see if any of that applies to your car.

As they say, look at the simple stuff first then move on to the hard stuff.

[Q45tech]

OBDII is a very different animal. A 96 with bad KS or hot coolant accelerates like a YUGO.Cannot compare a 91Q to a 96Q in acceleration when both are perfect.

[maxnix]

The last test drive done by senior Infiniti tech(1989) had the Consult pop the KS codes and the instant the timing retarded.Coolant is all new as is fan when the welch plugs were replaced last year.The first 15 minutes or so in the morning, the Q accelerates great. When totaled warmed up, it still chugs up the Sf hills, even WOT can't get much speed up the steepest hills.my '91 Q would fly up the big hills when trying to clear out the injectors on WOT.

So what did he discover?

Did the timing retard after is was wormed up to what temperature? did they replace the temperature sender when they replaced the coolant?

What were the KS codes that popped?

[qship96]

OBDII is a very different animal. A 96 with bad KS or hot coolant accelerates like a YUGO.Cannot compare a 91Q to a 96Q in acceleration when both are perfect.

Sorry, I have to disagree with the above....I noticed very,very little difference in acceleration with good vs bad knockers on my 96Q- main difference was light throttle tip in acceleration. MPG didnt change.

[goody90q45]

The last test drive done by senior Infiniti tech(1989) had the Consult pop the KS codes and the instant the timing retarded.

Was the test drive done after the KS were replaced or before? If before, were the codes the only reason the stealership replaced the KS? Did they ohm them?

.......The first 15 minutes or so in the morning, the Q accelerates great. When totaled warmed up, it still chugs up the Sf hills, even WOT can't get much speed up the steepest hills.........

I wonder if 15 minutes is about how long it takes for an FPCU to fully warm up?

Alexander- Please tell us why with all the $1000's you've put into your Q that the FPCU and fuel pump are still original. It's been suggested to you in every thread you start that these two items should be replaced but you keep spending $$ pulling the plenum off and replacing parts. Sorry to be an arse but tell us again why this 2 hour preventative maintenance hasn't been done.

[maxnix]

Goody has a real valid point. Maybe you ought to get that tech to take a drive with you with the fuel gauge hooked up.

For the money you spend, I would contact Joe, order the O ring, FPCU and fuel pump and just replace them all. Doesn't have to be Infiniti technician, just someone experienced and good. Steam clean tank if there is so much as a barely discerible film in it.
Modified by maxnix at 7:51 PM 2/13/2009

[alexander]

Fuel pressure was tested 8 months ago and all was OK, even on road test.No buzzing sounds.Infiniti tech road tested again both fuel pressure and KS's and that when the codes came up for failed KS.They replace them but that was not the problem. They did not say this could be the 'only' problem. Other dealers have said it could be just a bad wire somewhere. That's why some have said 'stop' pumping money in this car.I figure I will be replacing all parts on this car eventually so, just do it now.The plenum was totally cleaned out.This Q has new rear crossmembers, blue shocks etc.Eventually when I sell this car someone is going to get a great deal.

[maxnix]

Eight months is a long time. Did he test it for a full half your under driving load to see if the FPCU heated and fialed? It mayb e good intitailly, but faile when heated as when you demand higher pressure from the pump going WOT up the hill.

Most non digital results of these tests are not reported as OK or not OK. They are specific unit of measurements per unit time. You need to get the actual numbers and report back. Analog world is not black or white, but infiniitely varying shades of gray.

[goody90q45]

Infiniti tech road tested again both fuel pressure and KS's and that when the codes came up for failed KS. They replaced them but that was not the problem. They did not say this could be the 'only' problem.

The KS are supposed to throw a code to the ECU when they sense something out of range going on with the engine (fuel starvation?). The fact that they threw the code when the timing advanced tells you that they are working, not that they need replacing. If they really were dead a simple 5 minute test with a voltmeter would have confirmed it:



Is there some scrawny 10 year old with long arms that you can put in your trunk and have them reach in and unplug the FPCU to check the connection? You'd probably only have to remove one plastic screw in the trunk trim to get an arm in there. The FPCU is in the pic mounted to the right of the storage box near the PS speaker. My guess is that the connector on the FPCU will have scorching or burning which means you should be replacing the FPCU (and fuel pump).

If you do find a bad connection slip the kid a $20 bill because the stealership would have charged you $100 to do it.

Thanks Jared for the suggestion about Picasa. I got myself set up with an account and am back to posting pics.