1994 Infiniti Q45a won't go above 25mph

[morton27]

The story goes my wife was driving the car this morning and it would not go aboe 25 mph andthen it stalled. Started back-up and it got her home. Of course, just the night before I drove it with no problems. This is the second time it has happened to her. What should I check? Thanx for any help

[maxnix]

Welcome to NICO.

How about a little maintenance history?

Sounds like the car is in some fail safe mode.

Did you perform a power balance test the first time?

Had your oil changed recently by a quickie lube and fubar shop?


Modified by maxnix at 10:20 AM 1/31/2008

[Q45tech]

Yes, please post how and on what you have spent the $5,000 over previous 2 years [30k] in mainteance and repairs.

Sounds like the ecu is in fail safe mode due to a missing signal from 1 or more sensors. 'MAF" and or "CAS"................................but then again a worn out fuel pump can limit top speed and acceleration.

[Haitian_King]

Yes, please post how and on what you have spent the $5,000 over previous 2 years [30k] in mainteance and repairs.

Seeing as how it is his first post, have you considered the possibility that maybe this is his first issue with the Q? Maybe he just bought it and doesn't have that information? Maybe the first time it happened and then went away, he wrote it off as a fluke?

Sounds like the ecu is in fail safe mode due to a missing signal from 1 or more sensors. 'MAF" and or "CAS"................................but then again a worn out fuel pump can limit top speed and acceleration.

At least that gives him some different routes to take. Would have been really helpful if you gave him the link to the FSM so he would be able to take a look. Throwing acronyms around to someone possibly unfamiliar with them doesn't help.

The story goes my wife was driving the car this morning and it would not go aboe 25 mph andthen it stalled. Started back-up and it got her home. Of course, just the night before I drove it with no problems. This is the second time it has happened to her. What should I check? Thanx for any help

Morton27, here's a link to the Factory Service Manual for your Q's model year. This is the same guide that the Infiniti Techs used at the dealership. It has some flowcharts to help you isolate the problem as well as instructions on how to fix it. It's in .pdf format (Adobe Reader) so it's easy to view on your computer. Hope this helps.

http://www.nicoclub.com/FSM/Q45/1994_Q45/

[goody90q45]

You've heard ECU fail-safe mode and fuel pump issues. There's a couple of things to do to try and narrow in on the problem.

The easiest would be to pull the codes from the ECU. It's behind the PS kick panel and is a simple DIY that every Q owner should know how to do. The Tech Help section at Q45.org has great instructions for pulling the codes.

Have you been hearing what sounds like a swarm of bees coming from your trunk lately? When you pull the ECU codes if there are none (code 55) the problem could very well be the fuel pump/FPCU. You'll need to pull the trunk trim covering the fuel tank and unplug the fuel pump connector from the FPCU (in the background in the pic). Check the connector and pins for evidence of burning/shorting and if present your fuel pump and FPCU are probably toast. If they both look clean, try grounding the fuel pump as shown in the pic. This will make the fuel pump run on the fastest of it's 3 speeds. If this solves the problem it points to a bad fuel pump.

Let us know what you find. Good luck.

[morton27]

Thanks everyone for the help to date. Yes this is my first Q. I did write the first occurrence off as a fluke as it went away. No maintenance history as I bought the car used. No power blalance test performed and I don't let the quickie lube guys change the oil. I always od that myelf for obvious reasons. I will pull the codes form the ECU and listen for the swarm of bees as suggested and let everyone know what I find out.

This forum is awesome. thanks for the FSM link

[Haitian_King]

You're welcome. Always glad to help a fellow Q owner.

[morton27]

Well it was the wiring harness. The wiring harness in the vicinity of the AMM had loose connectors. Discovered while under the hood and bumped the harness with my arm and the car shut off. What a fluke. Thanks again for the help. Guys.

[maxnix]

Seeing as how it is his first post, have you considered the possibility that maybe this is his first issue with the Q? Maybe he just bought it and doesn't have that information?

No, the first issue with any previously owned automobile is how does the purchaser correct for the deferred maintenenance? For this, even an informed consumer must be aware of the automobile's design and operational requirements. Studying the FSM is the first step, but only that.

Why in IOM (where this post belongs), there is a requirement for posters to summarize recent maintenance history with each post.

[maxnix]

No maintenance history as I bought the car used.

The previous Infiniti dealer performed service is available from your local friendly Infiniti service writer whose good will you have cultivated. It can also be had from Infiniti Customer service in oral form when you register as the car's current owner.

But surely you know what you have done to mitigate the car's deferred maintenance?

[maxnix]

Well it was the wiring harness. The wiring harness in the vicinity of the AMM had loose connectors.

Then you might find a search on "Stabilitant 22" interesting.

Good thing to check all connections, especially bulb and wiring as PO may have used a Chinese one which will fubar that socket and give you interminable brake light out warninigs.

[AlabamaDan]

Good thing to check all connections, especially bulb and wiring as PO may have used a Chinese one which will fubar that socket and give you interminable brake light out warninigs.

So it's bad to use Chinese bulbs in a Japanese car? Sorry, I found that funny and couldn't resist.