Eighty7camarokid

iTrader: (4)

I have a 98 Z28, A4. I have run out of ideas as to why it will not start every time I turn the key. Sometimes it will start (about 10% of the time) and the other 90% it will just crank until the battery is dead. It has spark, I know this from using starting fluid down the intake. I have tripled checked the grounds, the fuses, cleaned the MAF, even had a new key made, and still nothing. Redline took a look at it, thought they fixed it (I am not 100% clear on what they did) but it started for them every time for about 2 weeks, I bring it home and within a week its back to its old self. Basically I am tired mof dealing with the car and I am completely out of ideas. I need a little insight to help me. Last time it was checked, it was throwing two codes: One for MAF low frequency and one for Purge solenoid valve. If I dont get it fixed, its off to the market place.

Link to old topic

Transam295s

iTrader: (2)

maybe try swapping the igntion relay out and seeing if thats the issue. Somethign easy to try and it may just work. Its in the engine bay fuse block. And if memory serves me right you can switch it with the one next to it. Just something to try.

LS1-450

iTrader: (33)

As long as the fuel pressure is good & the MAF itself is not damaged, I'd say to try a new PCM. Low reference signals to sensors can indicate PCM failures. I'd confirm that there isn't a fuel pump or clogged injector issue prior to installing a new PCM.

BTW, during a time when the car is running, tap the MAF w/ your hand. If the car stumbles, I'd look for a new MAF. Sometimes, tapping the PCM can identify a bad PCM.
However, like I said, if fuel system & MAF are good, try a new PCM. Good-luck

bczee

iTrader: (12)

I would say check the other sensors.. Crank and Cam. Clean the connections and get a scanner and check that you have output from the sensor why cranking.

andrew69_04

iTrader: (148)

check your fuel pressure first. if thats up to par check to see if your injectors are firing. sounds like your not getting any fuel if it will pop off with starting fluid.

loyolacub68

iTrader: (16)

Need to check fuel pressure, maybe a bad fuel pump? Does it start with the starting fluid or just pop. Do you make a habit of running the tank dry? That can lead to the fuel pump burning out on you.

When it does start does it stay on? Can you drive it normally?

EDIT: Just read the other thread from the link you posted. Gotta tell you, that sounds exactly like my car when the fuel pump went bad. I think you can replace them for pretty cheap. The fuel pump on these cars will work for short periods of time and then slowly start to die. Thats why a lot of guys that have turbos, SC's, or NOS have fuel pressure guages, because the pump will start to fail and the engine runs lean then BOOM.

You said you had initially tested it and the pressure started at 55 psi and then went down to 43 psi after 15 min. Sounds like the pump is going bad.

Eighty7camarokid

iTrader: (4)

Fuel pump is fine. I am trying the resister splice into the wires. I'll let you know what happens.

loyolacub68

iTrader: (16)

Do you have a friend with an F-body, switch his MAF/PCM into yours and see what happens.

Eighty7camarokid

iTrader: (4)

I dont know anybody else with a 98 A4

loyolacub68

iTrader: (16)

Well, if you run out of ideas you could always bring it into a dealer and have them tell you what is wrong. I used to do that at a dealer up near my hometown. Bring it in, tell them the problem, they tell you what is wrong, you say you don't have the money to do it, then you fix it yourself. It only worked a couple times but I was able to track down a couple problems.

john563

iTrader: (17)

I had that same exact problem. dealership told me it was the vats/lockcylinder,so I replaced it($$$$)well 2 days later it did the same thing.Swapt out the ignition relay for a new and never happened again

Lt1Porsche

iTrader: (6)

A lot of times your going to end up back tracking and rechecking things that you have already checked. I'd start by checking spark, fuel pressure, injector pulse, voltage @ MAF, Crank Sensor. Somewhere in that line you will find your problem. Need three things fire, fuel and compression. Given that im sure your timing is right your missing one of the three things. Track it down to which one. If its a security (VATS) problem you wont have spark. Ignition relay no spark. Fuel pump relay, no fuel. Bad fuel pressure reg., bad pump, clogged injectors, clogged fuel filter. Start by seeing if you can get her to run strickly using carb cleaner. Have one person crank as you spray. You WILL find the problem within this list. Good luck. You will get it. Oh, and it you realize your not getting current to multiple sensors or circuits chances are its your PCM. Locate the fuse distribution block under the hood and check both sides of ALL the fuses with the key on. Your looking for current or ground to all fuses and on both sides of the fuse. Look for an open circuit somewhere. If you have a fuse or a few fuses that are not getting current its your PCM. Best choices are starting at the Igition and Fuel pump relays. Good luck again.