I purchased my 90' Audi 90 Quattro 20 valve about a month ago from a guy in Vail Co. (elev. 8200ft). A lot of components had been replaced including timing belt, water pump, cap and rotor, spark plugs, coolant temp sensor, engine temp sensor. I have replaced air filter, fuel filter, O2 sensor and water temp sensor. The original Hitachi injectors have been replaced (previous owner) with the Bosch injector retrofit from 034 Motorsport. I live in Casper Wyo. (elev. 5200). Car ran very well and cruised easily at 75 mph on its 4 hour trip from Denver to Casper. Things I did notice was that it was weak on hills and i'm not talking steep hills but inclines. I found myself having to downshift into 4th and romp the throttle. When the secondary opened it would pull hard but then cut off like as if the A/C had been engaged, back and forth hesitation. I notice that it runs and accelerates very good if I don't go above 3500 rpm between shifts or open up the secondary above 3500 rpm. When it does go above 3500 rpm hesitation starts and throttle response worsens and stays this way through all gears at all rpms up until you shut off the car. The other issue is that the exhaust stinks as if it's running to rich. Car has been serviced and checks out well, my mechanic set everything to factory specs, but thinks that the issue could be with the injectors dumping to much fuel and if they were or can be calibrated.

Has anybody else done this injector retrofit and had any similar issues.

 

I put the same 034 injectors in and am having no issues. In fact, the 20V engine pulls like a freight train at ALL rpms from idle to 6500. the altitudes you mention are no problem for an EFI system, which automatically calibrates itself on the fly for altitude changes as a normal part of its operation. I think you need to look elsewhere for the issue. If the injectors are dumping too much fuel as your mech speculates, it is not the injectors themselves at fault, but the system controlling them which is your stock EFI system. Did the previous owner properly bypass the resistor pack with the 034 optional wiring pigtail, which is a simple plug in? Or did they cut and splice the wires, which is the $40 cheaper option? I ask because if the latter then someone should recheck the wire splicing job. The resistor pack is visible with the hood open behind the firewall just inboard of the large fuse box, which is in approximately in line with the brake reservoir.

DougM

 

I re read my post and felt compelled to emphasize the operating differences between what you describe on hills, and how my new to me 20V feels. We have steep mountain passes and serious grades and my stock (except the 034 injectors) 20V feels eager and powerful - easily accelerating up the steepest stuff we have including local mountain grades far steeper than are allowed on interstate systems.

So, something is up, but if my experience is any indicator, it is not the injectors. Does your tech really know this EFI system? I'm going to speculate not, because those are serious operating deficiencies, and him wondering if these injectors are "programmable" tells me he is not particularly well qualified to work on this system - a very basic EFI system by the way.

DougM

 

My mechanic use to work for a Porsche/Audi dealership for many years and has worked on all my German cars in the past, but has not worked on an Audi with this retrofit kit before so he was blind on the specs of these injectors. The car does have the plug-n-play harness so I know we are okay there. He did find a loose timing belt and fuel pump relay had a bad connection but that was about the extent; He set everything to factory settings., but wasn't sure if maybe there was a difference with these injectors that he should be aware of. I have given him the information from 034 Motorsports.
Another thought was maybe my catalytic converter(looks like the original) was bad and maybe i'm building to much back pressure, so I took it to my muffler guy, who just so happens is a big Audi enthusiast. He doesn't think my cat is bad but agreed the fuel mixture out the pipe was to rich. We may run a back pressure test to confirm this.
You are probably right about the injectors not being the problem but something else. Maybe intake manifold pressure, MAF sensor (I did check it when I changed the air filter and it was clear),fuel pressure at the regulator.
it just is weird that all runs okay until you hit that 3500 rpm. then it goes to poop!

Mike in Casper

 

Guys, this engine is outside my area of expertise, so I REALLY don't want to hijack your thread... but.:

I used to have an old AMG ML55 that had this same issue. It turned out that the problem was a failure of the changeover solenoid that was supposed to switch the position of a flap in the intake. At 3300 RPM, the vacuum-actuated solenoid would clode a little trap-door in the intake manifold. The closure of that trap-door shortened the airflow pattern in the intake and gave you a bump in hi-end grunt.

My changeover solenoid wasn't closing that trap door all the way, and the resulting airflow pattern in the intake was kind of a combustion chaos. This in turn threw the burn balance out of wack, started telling sensors that the fuel-air mix was wrong... just not a pretty picture at all.

On the advice of a friend, I pulled the solenoid because it was easy to get to on top of the engine. Guys, it was NASTY-caked with carbon on the inside, AND had a cracked vac line leading up to it, as well (my buddy said the cracked vac line allowed dirt into the solenoid, and the heat of the engine baked it on to the inner surface. REALLY smart guy).

I soaked the solenoid's internals with carb cleaner, blew it out with compressed air, soaked it again with some WD-40 and drained it. Replaced the vac line, reinstalled.

Never gave me an issue again for the next 10,000 miles I owned it.

Like I said, I don't want come off like a know-it-all, here. Your engine might be configured way fifferent than what I'm used to in the 12V. But your issue seems to hit a little too close for me to just leave you hanging, ya know?

Good luck, and let me know how it goes, please.

 

Which water temp sensor was replaced? The one at the back of the head is for ECU. A few things could be going on the knock sensors might need to be replaced or re-torqued common problem on these motors they can be replaced with the newer bolt through style sensors. Could also be a bad MAF. Checking the fault might shine some light on it.

 

Both the CTS and the water temp gauge sensor have been changed. I know the CTS plays a vital role but doesn't the water temp gauge sensor have some role as well? According to my mechanic (and he his very good)the car is reading no faults. I looked at the MAF visually and it's clean. What electrical tests should I perform on it? Knock sensor is a thought, haven't checked that out. What's baffling the f@#k out of me is the hesitation. It would be one thing if it ONLY hesitated at that 3500+ rpm mark and then quit, but ONCE it reaches that point it hesitates from that point on. Come to a stop, take off,....hesitation. Try to accelerate and if feels to have no power, and your pushing farther and farther down on the pedal to get her going, but...keep her under 3500 rpm and she drives fairly normal,....nice smooth acceleration with good throttle response. I can even hit the secondary for a brief moment let off before that 3500 rpm and it's seems okay. It's almost as if she has a mind of her own and punishes for revving her to high. LOL

 

If somebody would like to say "Hey LG, this car doesn't have an intake changeover," I would feel better...

Or, you could also go look at the following location I found for the part I'm talking about (which I'm now fairly CERTAIN is your issue):

It's located right near the MAF. It has 2 vacuum lines going into it and a plastic cap on one end. It's about the size of a 9V battery.

It has a vacuum leak, dude. Probably happened when you pulled the MAF to clean it. When the secondary fuel dump kicks in, the intake airflow path needs to shorten in order to compensate. If you have a vacuum leak at the changeover valve, the changeover itself won't happen, and your exhaust will stink with no power.

Somebody please either verify my line of thought or just tell me to shut the Hell up. You're killing me right now.

 

It doesn't have one you're not really helping if you're not familiar with the 7A engine.

 

Agree, LG the guesswork is killing ME! J/K....