Silly question but is it likely that there are any valves or a regulator on the old fule line between the fule pump and the engine?

also when you fit the phonic spacers are you supposed to fit a gasget BOTH sides so it forms the right seal or just one, or none at all, i dont know if tuffnol can be used a a gasget material.

another idea, could the powder coating be causing a poor seal? when we got it back i removed alot of overspill of powder coating that was on the nicely machined surface that was suposed to press up against the gasget.

i know on most cars this probelm would be caused either by a broken idle control valve or having the wrong air fule mix going into the engine and then the idle control valve wouldnt be able to adjust quick enough to compensate, so could the engine somehow be putting too much fule or too much air into the system when it's not being told to by the ECM?

this problem is definatly getting worse when the engine's hot, and the hotter it gets the worse it gets, i was under the impression that in a returnless fule system the fule didnt get hot so is it unlikely to be caused by something on the fule system? what about the blow-by gass recirculation system, the rocker cover is linked streight to the intake manafold could the gasses from there be throwing out the vaccum in the intake?

i'm pulling my hair out trying to think what the problem could be (not literaly though, i quite like my hair)

 

sorry i'f i'm double posting her but for the record i have an air flow meter at work, so we can actualy check things like that.

 

Dammit, I drove the car back from my girlfriends along a long quiet highway! At those speeds that car is a DREAM!!! Just gotta sort this niggle so I can go out driving it without worrying about getting arrested for angry revving noises!

Changing the awful spark plugs that were in it for new ones tomorrow or thursday - see if that helps, as at low speeds it miss-fires left, right and both centers!

 

This is a real silly one but just wondering after you swapped over the brake booster lines and the other canister lines etc did you reset/disconnect the battery for a little bit to reset everything

 

We didnt after that no, but I didnt think that would affect it? Isnt that all mechanical?

I also know that I may have some air in the coolant. So perhaps this could be a cause.

We never ran the engine with the radiator cap off to burp it you see...

An air bubble passing the coolant temp sensor might make it inject more fuel because it thinks it is cold.

I have an idea, that there may be an air pocket in my coolant. When the engine is started, the problem doesnt occur for a while.... perhaps because the coolant is flowing slowly... and the air pocket is moving slowly... so doesnt reach the coolant temp sensor, or it doesnt matter because the engine is cold anyway...

When I drive the car faster, the revving on its own gets faster... maybe because this air pocket is moving faster... and each time it passes the sensor more fuel is added, causing it to rev up then down....

It seems to be a good idea.... so ill try it tomorrow.

In the shop manual it says that idle control is regulated by the coolant temperature sensor.... this is looking promising... an air pocket changing the reading of that could cause the idle to go up and down....

I have searched google for this problem and it is VERY common. I find hundreds of people with the same problem on forums but no-one actually finds a solution or posts it!

 

Have you checked your vacuum levels and compared them to what the service manual says to expect?

 

Yeah resetting the factory ECU is very important as it will basicly tell the ECU to start relearning information again and forget about previous information...

But like Otter has said I really do think that you have a vaccumm leak... reason being is that it is fine when you are stationary but when you are driving it becomes eratic now the only real differences here is the volume of air that is passing thro the T/B or bypassing the t.b and into the plenum... I had a simmilar situation to yours a while back and after much looking around we finally found the hose that had fallen off it is at the back of the plenum chamber but underneath it... it is about a 3mm size tube -

did you check the air flow sensor on the intake pipe ?

 

The problem occurs only at idle when moving forwards or backwards with the throttle not being pressed.

I.e anytime the clutch is down when im still moving.

All other times it is fine.

This is why I think it is a major air pockets in the coolant, as I know for a fact its not filled up to the brim, nor has it been burped.

The shop manual says engine coolant sensor determines idle, and air pockets could cause it to inject extra fuel (to make the idle higher when coolant is cold), causing reving up and down at idle as the hot coolant, then air passes the sensor.

I'll try burping it tomorrow, as it seems the most likely cause to me, and I'll reset the ECM.

 

After a lot of searching all night I've found several people who had this problem, each one solved it by burping the coolant. I'll let you know how it goes tomorrow!

 

Good Work.

 

That's an obscure problem, never heard of it. Good luck fixing it. With the missing parts in, new plugs and hoping the coolant is the cause of the idle, it will run great

 

I had a problem similar to yours with my RA.

When I was moving slowly in traffic and I pressed in my clutch my RPM's would jump all over the place.

My mechanic figured out that it was caused by my throttle cable sitting on my headers. In the pics you posted of your engine bay your throttle cable looks close to your headers, maybe it is the same problem I had??

Congratulations on getting the swap done! Your car looks really good!

Later

Steve

 

Your saying the heat on the throttle cable could be causing slight fluctuations? It does run very close to my rocker cover.

 

I just tried bleeding the coolant - it seemed to work for a bit then it started doing it again. I then was just testing it over and over once it warmed up then and it stopped doing it. I think getting the many air bubbles I had in the coolant did something...

Anyway, when I move the throttle cable closer to the engine when its on, the car revs to a higher rpm, when i move it away, the car revs to a lower rpm.

If it is the throttle cable causing this then I think it may be because of the header's heat.

 

I also seem to get error P2101 a lot - throttle magneto malfunction... wonder if that is also a cause - says it is overheating.