stalled

[mortimer9]

96Q45 with 78000 miles stalled recently after just traeling at 30mi per hr.Started right up tho noted to have a barely noticeable vibration.Autozone OBDll reads PO100,malfunction in electrical cicuit for the mass air flow or volume air flow sensor.Code points to a possible wiring problem.i.e.short to ground,short to power,or an open circuit. #2-PO325-malfunction exists in circuit for knock sesor 1. kevin

[mortimer9]

no responce from OLM re:post of 2-6'07,stalled Q45&codes100&325. kevin

[goody90q45]

If you haven't done so already, the first thing to look at would be the MAF connection.

> Are male and female pins corrosion-free? If not, remove corrosion with electric parts cleaner and a toothbrush or equivalent and coat both connectors with dielectric grease.

> Is the connector fitting tight? If it feels loose or has been wiggled a lot recently the female pins in the connector may have opened up and not be providing a good connection, especially if corrosion is present. Get an eyeglass screwdriver and gently pry the female pins closed until they provide a firm connection.

> After you plug it in do you have a metal clip on your MAF connection to hold the plug in place? If not it may just wiggle loose again.

Do these few things to get a better connection at the MAF and see if it helps. Let us know. Good luck.

[maxnix]

What model?

They are probably in the FSM under diagnostics.

[Q45tech]

If you type P0100 or P0325 [one at a time] INTO GOOGLE you usually get the answer or device: MAF and Knock Sensor.

Then you look in FSM under these codes or devices for specific diagnostic proceedures.

95% of code numbers are generic and apply to all makes and models of post 1995 cars [1996 OBD2].

After 11-12 years of being the standard OBD2 codes should be well known to every vehicle operator/owner

[mortimer9]

Mike etal thanks.I cleaned the connector,MASand throtle body and cleared the codes,then ran it for 15min and it was great.The next day I drove it and it slalled badly.Tried again and it ran perfect after it was warmed up.Rechecked the codes and now just the 325 shows(knock sensor).Got rid of the 100code.I noticed that Ellissio maintains that stalling not ordinarily a Knock senor.I'm thinking(as outlined in the code explanation I got at Autozone) its a electrial problem.Appreciate your help. kevin

[maxnix]

No maintenance history, but I wonder if you have a leaky injector of some other rare failure.

[mortimer9]

Thanks,can you tell me what FSM is & where I find it.? kevin

[mortimer9]

Mike I did reply.Did you Get it? kevin

[goody90q45]

Mike I did reply.Did you Get it? kevin

No. I didn't get an email if that's what you're referring to. Try again?

You can download a copy of the Factory Service Manual (FSM) here:

phatg20.net

[Q45tech]

The MAF can have a bad external connector OR internal connections or some of both.

A symptom is erratic behavior as the temperature changes.

I have seen bad cold MAF that straighten up as they warm up and various converse versions............bad cold, good warm, bad hot.

Bad when the moon is FULL but good at other times.

Why you always swap and test a week before you are sure of a fix. OR JUST BUY BRAND NEW and assume a high probably of new working.

[mortimer9]

Mike,the retun post is on the series dated 2/13. I took apart the MAS&throttle body&cleaned thourghly though they looked like new.The connector revealed a slght discoloration on one flat ribbon piece(there are 4 that fit into the female side).I erased the 100&325 codes.I ran it at freeway speeds for 15 min and rechecked the codes and there were none.The next dayand before the engine was warm,it stalled,I checked the codes and the 325 but not the 100 was back.The Autozone explanation on that code suggests a electical cause(see first post).Your opinion. kevin

[maxnix]

Why you always swap and test a week before you are sure of a fix. OR JUST BUY BRAND NEW and assume a high probably of new working.

Swapping with a known good MAF is one way of determining if you need a new one, or if you're feeling lucky, a used one.

[goody90q45]

Sorry Kevin but you've tapped the extent of my knowledge. Anything else would just be a guess. The fact that she ran good after cleaning the MAF and TB and then crapped out a few miles later does seem to point to an electrical or MAF problem. Q45tech's advice to swap in a known good MAF would be a good next step. Unfortunately the G50 (3 prong) and the Y33 (4 prong) use different MAFs so you're limited in your choices. Good Luck.

[maxnix]

While he has an OBD II system, it is still a G50.

Wasn't there a post about the later OBD I MAF being able to be interchanged?

[Q45tech]

The problem is how to check a USED MAF.................I don't assume the USED replacement is functioning 100% until a few weeks of daily driving has occurred......................then it can fail a week later without warning.

It can drive you batty, when you change units and create different obscure problems.

The problem is solder and tension on the connector and socket transferring to the internal circuit boards and just car vibration in general which eventually takes its toll.

[mortimer9]

Mike, I thank your candor,I'm trying to download FSM,hoping to get information on electrical system.Kind of leaning toward malfunction of the kock sensor.Is it difficult to get at them?I have the 4 blade connector on the MAS with only 3 wires coming in on the female side.Your thoughts. kevin

[maxnix]

Knock sensors are probaboly bad, but won't stall car.

In CA, injectors go bad frequently. probably not the cause of a stall however.

since you are in San Diego, why don't you take it to the master?

http://www.jerrytucker.net

I know he has a Consult. And lots of qualified experience.

[mortimer9]

Brian,thanks.I've had work done by Jerry Tucker before-not cheap.I tried to access Phatg.20.net and downloaded the manual 3 times but so noway to bring it up.Sure would like to get it.How does one do a swap.Prices on new run 500.00. kevin

[goody90q45]

I tried to access Phatg.20.net and downloaded the manual 3 times but so noway to bring it up.How does one do a (MAF) swap. Prices on new run 500.00. kevin

I'm PC challenged (old f@rt) but I do know that you'll need Winzip to unzip the file before using it. Unzip it one time and save it and you're set to go.

Removing the MAF should be simple. On the G50 (should be very similar on your Y33) one end is attached with 4 bolts to the airbox lid and the other end is hoseclamped to the air intake tube. By swapping I mean you need to make friends with a local 97-99(?) Q owner or meet up with a NICO member who's willing to let you borrow the MAF from their car for a couple of days while you test drive.

[maxnix]

I've had work done by Jerry Tucker before-not cheap.

Knowledge never is, but it can be cheaper than throwing parts at it willy nillly. Failing and failed used parts can prolong your agony even more.

Seems like it would have to be worth something to get it diagnosed correctly and repaired so it operated reliably.

[Q45tech]

If you visualize that the MAF has a nominal 1.2 volt output at hot 650 rpm idle and maybe half that when the engine shuts off..........the ecu shuts down with less than 1.0 volts from MAF.

It is really difficult to to CAPTURE the voltage error..............ckicken or egg what caused what..............did the sudden drop in MAF voltage kill the engine or did the engine dying from something else kill the MAF voltage as the rpm dropped.

Why you substitute a KNOWN GOOD MAF after you measure fuel pressure under extreme rpm.

An intermitent FPCU can behave similiarly but that can be caught by the PSI going below 34.

[mortimer9]

Mike,trying to understand" Winzip to unzip".Is that a password?When I download infinityQ45,96yr.it asks to either open or to save.I've tried both options but then nothing further happens. kevin

[goody90q45]

Mort- Someone else needs to help me here. I'm only good at the basics (old f@rt school, learned on a card reader) and rely on my kids to get me through the tougher PC questions.

I was able to download the .rar file to my desktop and open it up directly from there. The file is compressed (.rar=zipped?) meaning you need the program Winrar (or equivalent) to uncompress (unzip) it. I'm pretty sure you can download this program for free.

Hopefully one of the more PC-versed members can come on and give you more details. If not, get one of the grandkids to walk you through it. (LOL) Sorry I can't be of more help.

[maxnix]

rar is a type of compression, like zip.

Google Winzip or tugzip. Download and install.

[mortimer9]

Mike,thanks,finally got manual on line&now digesting.The car at present is not misbehaving.Hoping the cleanup of the connector,MAS and throttle body has taken care of it.I have a slight valve gasket leak and the knock senser code persists. kev(mort)