Toyota Celica Supra Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
406 Posts
Discussion Starter #1
Hey there,

Just found this out tonight by chance =)

If I slowly bring the revs of the car (82 P-Type) up towards 2000, no problems occur. BUT, as soon as I hit about 1800ish and hold it there, the revs will drop to about 1200, then jump back up. Repeat, repeat etc...

If I put the revs just below 1800ish, or just above, there is no problem =)

Is this possibily where the TPS changes its resistance scale?

It doesnt affect power or drivability at all, just a little quirk, so Im not really worried. Any input would be nice though!

Thanks,

Aaron
 

·
Registered
Joined
·
35 Posts
im guessing its an auto right?
if so that could be you fooling the auto transmission? Thinking its going into the next gear will drop its rpm.
 

·
Registered
Joined
·
1,089 Posts
Yet another poor soul like myself with and 82 "Vacuume controlled everything!" I swear (and I do ... allot!) that even the signal lights run off of engin vacuume on 82 cars.

Have you checked to make sure that the vacuume advance isn't sticking???

If it was grabing and not advancing as it is suppost to the added vacuum pressure of higher RPMs could cause it to suddenly "POP" into an advanced state at the higher RPM Range. I'm think that would be enough of a power surge to give you a little kick in the pants. :nutkick:

I'd try to clean and inspect the advancing linkage on the distributer and throw a timming light on the engin. if the timming mark does not move between 0 and 1800 rpm and then suddenly jumps then you still got a problem. If not it would be a good idea to clean it anyway 'cause thy tend to stick.

Let us know if this fixes it and if all else fails...:hitit:
 

·
Registered
Joined
·
406 Posts
Discussion Starter #6
meh

well, I played a bit with the vac advance on the dizzy, but it didnt really change anything.

Im wondering if its not the TPS or somthing thats being finicky... maybe a vaccum leak on the manifold?

Whatever it is, Its definatly not hurting the power of the economy. If anything, its helped my gas mielage. I got 260miles on the last tank... yay! =)

Aaron
 

·
Registered
Joined
·
1,089 Posts
Do you know how to check for intake manifold leaks???

Get a propane torche (like the ones plummers use) and put about 2ft. of rubber hose over the end. DO NOT LIGHT IT! :burn:

let your engine warm up and when it gets a nice slow idle simply pass the propane gas over all the places you think there could be a leak. If there is a leak the propane will raise the idle. Piece of cake ... and a real time saver.
 

·
Registered
Joined
·
591 Posts
does the the engine get rough when it drops speed? if it's the tps it would get rough. what does the tacho say it is idleing at?(maybe fastidle sticking open then shutting (unlikely)) vacuume leak, again, would be causing a fastidle until the engine twisted enough at 1800 to seal the leak(have to be a small one) and you'd definately hear it with the speed variation your talking about.

try a bottle of fuel system cleaner. if the engine is going lean then back to stoich it could cause that but i think it would tell you via the check engine light.

one question...when it drops to 1800 and you press the gas a little more does it incease to say 1500-1800 or to 2k-higher?
 

·
Registered
Joined
·
72 Posts
That's just about the RPM where you will notice an EGR surge if things are not working properly in that system.
 

·
Registered
Joined
·
591 Posts
i solved my egr problems by disabling it and getting another mpg in city.

i just gotta remember to plug it in agian before emissions testing lol
 

·
Registered
Joined
·
406 Posts
Discussion Starter #11
hmmm

Disabling it eh? How did you go about doing that?

Ive thought of that too, but for HP reasons...

Aaron
 

·
Registered
Joined
·
591 Posts
disabling the egr like i did it.

out of the top of the throttlebody are 3 vaccuume lines. 2 of witch go to a circular brown thing called the egr vacuume control modulator. i disconnected one of them at the little brown thing and one at the tb. then looped the ends around and reconnected them to the connector beside it at botht he egrcm and the tb. then there is a vacuume line coming up from under the intake that goes to a little T-head. then the hose splits and goes to the egrcm and the actual vaccume plunger for the egr valve at the intake manifold. i disconnected one of the lines form the t head and the other from the egr valve. then i looped it around on itself and connected it to itself. i realized after doing this there is a MUCH easier way to bypass the egr system.

the easy way:

by your thermostat is a small blue bsv. this vacuume switch controlls whether the egr system comes on at all or not because of engine temp. disconnect both lines from the valve and plug them. your done...

REMEMBER:if your county has emissions testing you will not pass if the egr system is disabled.

few good reasons to do this...better throttle response and more power due to the lack of exhaust gasses reentering the intake manifold. secondly. keeps the egr system from getting carbonized so it doesn't work anymore and you get to pass emissions every time(unless you forget to turn it back on.
 
1 - 12 of 12 Posts
Top