Many issues.

[98QuattroAFour]

I'm very new to the page so please refrain from flaming me about anything. To begin, I am a mechanic and can do absolutely any labor nessecisary, with that being said this is my first Audi, my first German vehicle, and my first awd vehicle. I live in South Louisiana and emissions is no issue for me.

I have a 1998 A4 Quattro 1.8t
I purchased it about 7 months ago for $400
I recently installed a boost gauge to start diagnosing some wierd hesitations.

At part throttle right as I build boost the car will slightly here back and forth, with the boost gauge I can see it cycling from ~3-6 psi back and forth. This only happens from about 2k-5k rpm. 5k+ it sits steady at 8psi.
What I find really strange is that at WOT I get a max of 5psi and no jerking through my entire rpm range.

I think that will be my first problem to try and solve. Thanks for any input!

[Davdraco1]

Check for boost leaks.

[b5a4erik]

Good luck, man. Welcome.

[98QuattroAFour]

Check for boost leaks.

Would a smoke machine be a good was to test for boost leaks? I removed about 3/4 of the vacuum system already because it was falling apart and leaking everywhere. I know I don't have any leaks after the throttle plate. Can I just smoke everything before the throttle plate too?

[Davdraco1]

http://www.audizine.com/forum/showth...st-Leak-Tester

I did something like this but with a 90 degree so it's easier to use. I attached mine into the TIP and then you just get some kinda spray soap from under your sink and start spraying where you hear a hissing sound come from. If it start to bubble there is your leak. A smoke a machin would work but that is easy and under 10$ altogether.

[a4kamila6]

http://www.audizine.com/forum/showth...st-Leak-Tester

I did something like this but with a 90 degree so it's easier to use. I attached mine into the TIP and then you just get some kinda spray soap from under your sink and start spraying where you hear a hissing sound come from. If it start to bubble there is your leak. A smoke a machin would work but that is easy and under 10$ altogether.

^^^^^^^ soap and water, windex and soap, you can even use that hvac leak detector stuff calgon blue or whatever.

soap and water works for me. spray everywhere you suspect a leak. if you dont have a boost leak tester or dont feel like making your own, get a buddy to hold the rpms at around 2,000. works for me

[98QuattroAFour]

I did a boost leak test and found one more leak. I fixed it. But I still have the same problem. The hesitation and jerking seems to be more intermittent now, but I still only get 5 psi at WOT and 9 or 10 at half throttle.

[seanf86]

I did a boost leak test and found one more leak. I fixed it. But I still have the same problem. The hesitation and jerking seems to be more intermittent now, but I still only get 5 psi at WOT and 9 or 10 at half throttle.

how does it idle? I had weak coils and it caused some surging/ violent jerking because it would missfire under load but not enough to set an engine light, I pinpointed the poor coils by having the scanner open on individual cylinder missfire counters and replaced the coil that that would set the one or 2 random missfires. It would also cause it to chug at idle every now and then.

[98QuattroAFour]

It idles great. And since I have means of checking misfires with a scanner I'll do it in just a few minutes.

[98QuattroAFour]

OK so this weekend was my weekend to finally do my timing belt, water pump, and power steering pump. I gother side tracked and forgot to check the misfires but when I tore my car down I found that the timing was a tooth off. That was probably some of my sluggishness.

[98QuattroAFour]

OK so I got all my work done. New timing belt, water pump, and power steering pump.

I drove the car for a bit with the scanner hooked up and did get a few misfires from 2 and 3 which are my 2 cylinders with original coils. I also noticed the maf sensor reading some wierd numbers.

I know I should replace my coils.
Does anyone know what the MAF should read on these cars?

- - - Updated - - -

Here is a link to a short 2nd gear pull. You can see that my boost spike and then goes down to 4 or 5 psi.

[98QuattroAFour]

https://youtu.be/KTOeLcRwwlI

[seanf86]

OK so I got all my work done. New timing belt, water pump, and power steering pump.

I drove the car for a bit with the scanner hooked up and did get a few misfires from 2 and 3 which are my 2 cylinders with original coils. I also noticed the maf sensor reading some wierd numbers.

I know I should replace my coils.
Does anyone know what the MAF should read on these cars?

- - - Updated - - -

Here is a link to a short 2nd gear pull. You can see that my boost spike and then goes down to 4 or 5 psi.

if you have new plugs in there and its getting a few misses on 2 and 3 yes definitely change the 2 coils.

[98QuattroAFour]

The plugs have about 10k on them. I just purchased 2 coils. I'll be putting them on around 430/5:00. Central time.

[98QuattroAFour]

OK so I changed the two other coils and now it doesn't hesitate as much but the boost still does the exact same thing.