itradem

So, after allowing the temp gauge to reach the normal operating level, I decide to get on the gas, but only see a 8-5-8 boost pattern. The problem persists for about 10 minutes, until magically I have 10-8-10 and A LOT more power.

This ONLY happens after cold start-up, and now happens about every time I drive the car. However, fresh oil seems to cure the problem for a few hundred miles?!?

Any thoughts?

Jeff
94 VR
M2 DP
RB Dual Tip
RB Intake
Hose Job
9.5# Flywheel

skunks

omg, dont drive hard when cold. i suggest you keep it below 3k untill fully warmed up (at least 180 degrees)

BTW: When cold, your double throttle is closed and your running on different fuel maps.

RonKMiller

Ok, I'll take a stab at answering your question - but it comes with an admonishment:

When the engine is cold, all of the sealing surfaces, rotors, turbos, etc. are not sealed completely because of temperature differences in the mass and composition of the components, hence blowby and lower output.

Your engine is NOT warm after cold start even though your temperature gauge (whether it is stock, aftermarket or computer driven) tells you it is. The only thing it is telling you is the coolant is warmed up. It takes approximately 15 minutes of continual driving (not idling) to warm up your engine's metallic parts (and they are the ONLY ones that are important) to operating temperature. How do I know? I have thermocouples installed under each leading plug on both rotors with a
readout inside on a "Rotor head temperature gauge" inside my cabin. It always lags far behind the reading on my water temp for 10 to 15 minutes after cold start. During normal driving everything settles down around 185 F. Oil temp is a better indicator, but still lags.

Now the admonishment: NEVER EVER boost until your engine is completely warmed up. It is probably one of the leading causes of premature wear and will harm the engine and turbos. Also, never boost for at least a couple of minutes before shutdown. It is critically important to let the engine and turbos cool down completely before parking it. This really goes for ANY engine, turbo or na.

My advice: wait before boosting and let the car's coolant system do it's job before shutdown, or buy a turbo timer if you can't stay off the gas!



Later.

CantGoStraight

Haven't had the car long have you ? ? ? ? and you will surely be disapointed when you fork out 5k for a new motor, and another 1500 for turbo's....just keep driving it had before it's warmed up and you will do just that. Ronk is all over the problem your encountering and if you keep doing it soon you will be boosting 5-85- when its warm and wouldn't have had a clue.......

itradem

RonK,

Thanks for the insight on the engine warm-up period. I guess that everything else I had read (biglist, forum), up until this point, suggested that I stay off the boost until the temp guage reached the mid-point; looks like I'll be adjusting my understanding and driving habits. I'm already waaay on top of letting the car cool down and staying off the boost before shut-down, but thanks again for the sound advice.

Can'tgostraight,
I have owned this car for 5 years now. It has 64K miles on the ORIGINAL engine and turbos, and I maintain it meticulously. Do you know the cost of a new engine and turbos from first hand experience, or are you just providing them to me in case I'm some sort of dumba$$? Your advice is the kind this forum can do without.

Thanks again RonK!

Cheers,
Jeff

RonKMiller

Hey, your welcome.

Yeah, there's a lot of what I call "jerky boys" lurking around - they basically don't know **** from shinola and have an attitude problem. Overall I think you'll find that most of the guys here are really pretty cool and will always give you good advice. You'll find that your engine can and will last a looooongg time if you take care of it and you obviously do. Just about everyone here who loses an engine does it because of improper mods, or expecting too much hp out of 1.3 liters.

64K is a great time to do all those issues that will keep it reliable: vacuum hose job, replace all hoses, belts, thermostat, ast, etc. I think the downpipe is a great mod (and cheap too). I keep all my old parts just in case someone in the future wants to return it to stock.
I'ts worth a lot more than modded, and there will be a day (hopefully a long time from now) when you'll sell it.

I love mine so much there is no way I'll ever let it go.
(Although I was tempted the other day drooling over a new Porsche Turbo at my local dealer for the paltry sum of $120,000 - without options!)

Later.

turbojeff

iTrader: (30)

Nice theory Ron. The major cause of the lower boost is the double throttle control remains closed when the engine is cold, this cuts off 2/3 of the intake area in the throttle body. = Less boost when cold. Simple as that.

I'm sure that the rotor sealing might not be as good when cold but I'd venture a pretty good guess that it won't have a big effect on boost levels (say double throttle control is disabled/removed).

Jeff

CantGoStraight

Itradem,
Sorry my post came across the way it did. While Ron is much more tactful in admonishing you for hard driving while the car is still cold I was letting you know this could be an expensive mistake especially if the double throttle is disabled. Nice to know you have had (and hopefully enjoyed the car for 5years. I've only had mine for 2years, and have two of them (one is completely stock with 76k and the other has 83k on it ) Again my appologies for the attitude if any was implied. Jack