Just got a 94 VR-4 / fast then slow

[KenMacG]

Definite newbie here...

Bought a very nice looking green 94 VR-4 with 100k miles. Everyone (including the local Smogcheck tech) suggested replacing the timing belt, since the history on the car is not completely known.:violin:

I had the local dealer do some work a few days after I bought the car. They replaced the timing belt, water pump, all fluids, and a couple of hoses. They said they could not find anything wrong with it. Sounds simple enough. Car currently runs quiet and smooth, but now that I have had time to properly drive it and pay attention to all the details, I have noticed one twist. When blasting off and the engine is cold, the boost meter pegs at +15 and it goes like a bat out of you know where. When hot, the meter only shows +7 and even teenagers in the back seat can tell the car is a lot slower. IS THIS NORMAL???? Yes, I read here that the meter is not a true boost indicator, but ???? I have lurked around here and read everything I can. As far as I can tell, this car is completely stock, with add ons, no hidden aquarium valves, etc. If this is normal, is this an indication of how poor the intercoolers work?

R, Ken
:confused:

[KenMacG]

Sorry, I meant to type: the car has NO add ons (yet!):)

I bought it from the original owner, a little old lady in Pasadena... not joking.:D

[ADLER]

you will notice a pretty big difference in outside temp changes. if it is 30 degrees outside your car will run much better than if it is 80 degrees. pretty standard. get an aftermarket boost gauge too, just so you can really see what's going on. the stock one is worthless.

[detpac]

I would change the O2 sensor. That seems to be a common problem.

[KenMacG]

OK, thanks! I am looking at boost meters now. I take it that I need a completely new kit connected to a hose under the hood, separate from the factory "turbo flow meter", right?

I have had an O2 sensor problem with my turbo Volo. Volvo took it out and measured the DC resistance, which was ok, so they put the old one right back in. They claimed that was a fairly relable test of O2 sensors. Does anyone know if that is true, or hogwash?

When you say that O2 sensors are a common problem, is that for slugish hot engine symptoms like my VR4 is showing, or are O2 sensors just a problem in general with these cars and age?

Glad to finally be able to communicate with other VR4 owners, I really think the technical people at my small local Mitsubishi dealership are not really up to doing more than basic service to these sophisticated cars. For what it is worth, I just returned this morning from visiting the annual LA car show. My goodness, times have changed in the last 5 years. The car world seems to have generally split into two different worlds. Slow, uninspired, $20k cars, and fast, big engined, $70k-$200k cars. The world of high performance mid-priced cars seems to have almost disappeared. The Mistsubishi exhibit was a little disappointing, cars were 200 HP or less, SOHC engines, no turbos in sight, NOTHING that compares to a VR4. Of interest to me were the New Beetle Turbo "S" (180-200HP), the upcoming GTO with a big engine (factory starts production in a month), the Lotus Elise (hits US shores in April 04), and I was surprised that the current new twin-turbo V8 Lotus only costs $70k FOB GA.

Ken

[Racer 007]

Originally posted by KenMacG
I really think the technical people at my small local Mitsubishi dealership are not really up to doing more than basic service to these sophisticated cars
remove old oem part
install new oem part

yup, that about sums it up.

[detpac]

Originally posted by KenMacG
I am looking at boost meters now. I take it that I need a completely new kit connected to a hose under the hood, separate from the factory "turbo flow meter", right?

This depends on your boost meter. You will have to run a new hose most likely. If you get a boost controller as well, it is a one shot process. They go together well.

Originally posted by KenMacG
I have had an O2 sensor problem with my turbo Volo. Volvo took it out and measured the DC resistance, which was ok, so they put the old one right back in. They claimed that was a fairly relable test of O2 sensors. Does anyone know if that is true, or hogwash?

More than likely is true for most vehicles. Ours seems to be slightly different. Mine tested well but were still lazy. Once I had them changed, much better.


Oh, and WELCOME.

[The Lurker]

KenmacG hows the car boosting lately? Is the problem consistent?

[KenMacG]

Now that I have had time to drive it more, here is a more detailed description of what I am noticing. (I keep the the VR4 in the garage for weekends/fun, and do not drive it to work everyday).

When I first bought the car, I drove it 3 or 4 times, throttle seemed a little jerky, ie it mostly wanted to speed up (+15 boost!) or slow down. I didn't notice much else before I turned it over to the dealer to do the 120k service including timing belt.

After that work, I immediately noticed that throttle control was very smooth and continous in range. Car was quiet and more drivable in an every day sort of way. I saw the boost gage would be at +3, +7, +10, or +15 depending on how fast I wanted to go. Seems that is the way it should be. I thanked the service people for having done a good job on the car, although they put the unidirectional tires on backwards (quickly fixed!).

I could not help but blast out of my neighborhood down a little used country road two blocks from my house. Typical outside temp has been low 70s here. Engine obviously cold, boost meter pegs at +15, in ANY gear if I stomp on it, acceleration tears your head off (must remember to take deep breaths). It will blast +15 again two or three times along the way to where I am going. Park the car an hour or two while eating/shopping. Start the car and drive home. The engine starts up quickly showing warm coolant temp before I get out of the parking lot. It will not show boost above +6 or +7 no matter what speed or gear, and feels slow. Don't get that car surging out from under you feeling like when cold.

On one day, longer drive, having an unusually (for CA in the winter) warm (80-85) outside air temperature, after about two quick accelerations showing +15 boost and then driving 20 miles at 55-60 mph the car won't show boost above +6 or +7 under any speed or gear, and believe me I tried. Notice I have not turned it off. Car actually "feels" sluggish in acceleration. Getting on the freeway would not have impressed anyone.

Another day, took the car back to the dealer to do the transfer case recall, and complained about the performance. They said there is nothing wrong with it. On the way home, floored it, boost +15, whoopee! Me and my son's friend in the shotgun seat were all smiles, and my son following us in the chase car later said he could smell burned rubber. 10 minutes later, +6 or +7 was all it would do again, and the passenger very much noticed the difference in performance.

Today (temps 69-70) I resisted the urge to go fast near my home on the outbound leg and kept the boost meter in the negative range. Drove 15 miles to first place, parked, 20 miles to a second, parked, 10 miles to a third, parked, all the while driving like Dolly the sheep. Car is obviously warmed up, I even had the AC on for a short while to cool the interior after parking in the sun. On the way home, I floored it once, not expecting much, and low and behold +15 and everyone get out of the way!

Conclusions. Not totally sure yet, however, performance seems to be influenced more by how hard I have driven it in previous hours, actual engine coolant temperature (hot or cold) doesn't matter much. It is like I am guaranteed two or three extremely quick starts per DAY, after that, forget it. So, is there consensus this is or is not normal for these cars? Thanks guys.

R, Ken

[barf]

No, that is not normal for the performance to change that drastically.
I would check all your hose connections (if you haven't already) and make sure they're all tight. Possible, you could have an intermittent boost leak?

[detpac]

I agree with barf, check everything twice. next problem would be O2 sensors and IAC motor cleaning.