I have encountered a small (hopefully) problem with my engine, it starts and runs perfectly for about 5 minutes, then the revs start surging, like its
drawing air from somewhere.
I have recently modified the inlet plenum to get rid of the TVIS thing and lower the bonnet line clearance. I left the TVIS sensor connected and just
clipped it to the underside of the plenum. I dont fully understand the TVIS thing, but could it be something to do with that? Any other suggestions?
I haven't fully looked into it yet, as there is no exhaust or exhaust manifold at present and things get quite loud and hot quickly. The only
reason it has been run recently is to test the various dash gauges, which brings me to my next question....Does this engine have a separate oil
pressure sender and switch? or is it the same thing, on the exhaust side of the engine, below the cap?
I bought the VDO gauges and the oil pressure sender that came with the gauges has three terminals, where the standard one on the engine only has one,
any ideas?
Sorry for the multiple questions.
Sounds like the cold start wax stat unit is finally closing on the throttle body after warming up and it's drawing air via an air channel.
There's a description of TVIS removal here http://www.redmr2.com/mr2/tvis.htm
Oil gauge is as you say, the point below exhaust at front. I believe the car with an oil gauge fitted doesn't have a light.
Cant help ref 3 wire sender.
[Edited on 7/2/05 by Rob Lane]
quote:
Originally posted by albertz
runs perfectly for about 5 minutes, then the revs start surging,
, as there is no exhaust or exhaust manifold at present and things get quite loud and hot quickly..
A surging idle is usually a symptom of air bubbles in the coolant, they tend to collect up in the throttle body so the wax stat remains open (no
coolant to warm it up and close it) and the ECU gets rather confused .
It may also be due to the lack of exhaust backpressure?
The engine should run fine without the TVIS.
[Edited on 7/2/05 by ChrisJLW]
Check the rad cap and coolant bottle cap are airtight and in the case of the coolant bottle/overflow tank, the plastic cap isn't split or
cracked. thats the most common result cause of the problems you are facing.
there is also a mod available to create a manual choke and do away with (bypass) the wax stat.
Kelvin
[Edited on 7/2/05 by Kelvin]
Excellent, thanks for the info and the tips, will try again next weekend and let you know how i get on.
Unfortunately due to the noise, i cannot really work on the engine at nights.
The air bubbles thing is a possibility as i have been refilling and loosing the coolant with alarming regularity, mainly intentionally it has to be
said.
Just out of interest, when i noticed this problem and switched the engine off a puff of steam escaped from the radiator cap, there is a possibility
that it was not tight in the first place.
Also, the thermostat does not appear to be working properly, as the hoses get very hot on one side and cold on the other. However, i have removed the
stat and tested it in a pan of water on the cooker and it worked fine.
Maybe the above gives someone some more clues??
I think that its air in the coolant lines. I have the same engine and had the same problem. Solved by burping air from the system using the front
bleed valve at the front of the car behind the spare tire.
The TVIS is not essential, but it is there to improve low end torque. TVIS closes one set of intake runners below a certain rpm to increase port
velocity. Above that rpm a solenoid activates a valve to open those butteflies and the air flow increases.
I know a number of people that removed the TVIS when they turbo'd the 4AGE and they are now putting them back on. It only takes a few cm of space
of the head to keep it. If you are not planning on replacing it, then block off the vacuum hose to the actuator.
Steve Graber
Edit - Oil pressure: The stock gauge uses 2wires. I have the 1985 instrument cluster in pieces at home and I can tell you exactly what goes where on
the stock gauge at least. If I don't get back to you within 12 hours, message me or email me. I am a bit forgetful these days.
Now that I think about it, one wire says IG+ and the other says Oil Sender...
[Edited on 2/7/05 by sgraber]