Can't get it to go over 400 RPM, Win a Drivers spot in race!

[carl johansson]

Ok guys,
thaks to Cre and Bryan's help, I have put a cresida block into my 87 supra - 7 MGE NA.

So i tried to fire it up, and it starts, but it won't idle over about 400, and eventually it will die. Pushing on the gas petal will raise it to maybe 500 RPM, but thats it, it will not rev past that. Also, i don't know if it helps, but after 30 seconds of this, the exhaust maniford was so hot it was smoking, and burned my fingers.

Over time most of the uneccisary stuff has been pulled from the engine - we use it in 24 hours of lemons racing, so alot of the vacuum, cold start etc have been removed.

I have checked the distributor position 2X, it seems OK, (using FSM procedure of looking through oil cap filler, seeing the nose of the cam, then backing it up till the mark on the pulley aligns with the 0TDC on the timing belt cover) assuming that the nub on top of the gear that lines up with the mark on the distributor body, well it's not really a nub, but a shallow hole above the gear. . The "nub" is identified in the FSM.

Anyone have any ideas for me to try? Anyone who can get this running correctly, will win a seat as a driver at the next race, (you will have to pay your own travel, but we will cover your entry fees)

[btwilson86]

Setting the dizzy that way should get it close, but you will need to fine tune the timing with it running. If you havent already, fire it up and slowly rotate the distributor and see if that helps. If you can get it running long enough to reach operating temp, then jump the diag box and set the ignition timing to 10 BTDC. I'd like to rle out ignition timing before moving on to other possibilities

[btwilson86]

Oh, and I cant remember if its advanced or retarded timing that makes the exhaust hot (i want to say retarded), so I'd start advancing it if that's the case

[cre]

Let's try to keep this more politically correct guys.

Mr. Wilson is right. If the spark is temporally challenged the exhaust temps are hotter. If the spark is advanced (see: SUPERSPARK! and Gifted Spark) more heat is absorbed by the engine and EGT is lower.

Carl, can you give us some more info on what all has been removed? Is the Fuel system still in tact? Is the TPS properly calibrated and have you tested the IDL switch? If you're not using the ISCV where have you plumbed in your throttle bypass inlet?

[carl johansson]

Originally Posted by cre

Let's try to keep this more politically correct guys.

Carl, can you give us some more info on what all has been removed? Is the Fuel system still in tact? Is the TPS properly calibrated and have you tested the IDL switch? If you're not using the ISCV where have you plumbed in your throttle bypass inlet?

Oh boy Cre,
now you moved right past my expertise. My job on this team is suspension, Tires, and logistics. I got thrown ito this through a series of unfortunate events.
The guy who has done all the electronics and engine work, knows this engine, and the plumbing and electronics has had a rough 3 weeks, watching a family member die, and having to make decisions about when and if, etc. So that being said, he has been out of town for 3 weeks. And unavailable either emotionally of physically during that time.

My backup technical advisor lives in Detroit, (me and the car are in California), so it's tough getting ahold of him, with the time change and work schedules.

Originally the Engine builder and i were going to do this engine swap 2 weeks ago, to have it ready for testing, before the 24 hour race this coming weekend. once he became unavailable, I was the only option. i'm doing my best, and you guys have been a big help, but lack of knowledge and running all of this solo, that has been a challenge.

Essentially i pulled the old engine, that had run strong for 225 hours of racing, and tried to carefully switch over everything to the new motor, then tried to hook up the wiring harness exactly like it was. I did label everything I unplugged, and am sure i have those parts replugged into the correct place. Where I fell down, is i did not mark the things that were previously unconnected and unused, It didn't dawn on me that I would be left wondering if i missed something after the switch.

So to try and answer the best I can:
Don't know what the ISVC is, so can't tell you what we have done, i assume we have removed it, and if we remove it, we typically plug whatever vacuum lines there are.
I believe the fuel system is in tact, but we do not use the cold start injector, or the EGR system.

I can tell you that on the top of the intake manifold, there is a fitting with a banjo bolt and a sensor. the banjo bolt tube leads to the top of the fuel rail. The tube is in place, byt there is nothing plugged into the sensor.
There are 2 cut off wires dangling there, black and red, and red and black.

I think the TPS should be OK, it was working fine, when it came off the old engine.

I just got a late recruit arriving, so first things first, we will fool with the timing - hopefully, thats all this thing needs!

[btwilson86]

The ISCV is the Idle Speed Control Valve. It plugs into the top portion of the intake manifold towards the front of the engine, and I believe it has two coolant lines running to it, as well as a 6 wire connector.

The "sensor" on the intake with the banjo bolt sounds like the cold start injector. From your description, it sounds like this is physically present, just not plugged in.

The IDL circuit is a part of the TPS. I believe it tells the computer that the throttle is closed, and that the engine should be idling at that point.

[cre]

A lot to cover here and I can't get to it all at once.

The TPS has a switch inside (IDL) which is used to help the ECU know when to run the ISCV (Idle Speed Control Valve). If it's not properly calibrated or the switch is damaged idle will be erratic and/or low. It's the first thing I'd check. See here for details on properly calibrating the TPS. See here for testing info on the ISCV. It's unlikely that someone whould have removed the ISCV but it does happen in which case you need to add a tunable air inlet (some people use the throttle stop or misuse the dashpot or drill a small hole in the throttle plate (NOT recommended) or add a needle valve with filter to a vacuum line that's after the throttle plate).... The argument is that it's for simplicity. EDIT: I forgot that we were talking about a MKIII for a minute there. Any alternative idle control would need to source its air from in front of the throttle plate and bring it back in behind the throttle plate.

I wouldn't have deleted the EGR.... Especially not on an endurance vehicle. You lose the benefit of enhanced cylinder cooling when at part throttle and it's off when throttle is 65 or 70% or higher. But that's your call. If the VSV with the cut wires is back by the #5 and #6 cylinders it's either for the ACIS system or for the EGR (the wire color codes are for the EGR VSV)... Either way you should remove it completely if you don't want it and cap the vacuum lines or you may have a vacuum leak there.

[carl johansson]

thanks guys,
Problem was timing, apparently i had missed by a tooth or 2 on the distributor. once got that fixed, it fired right up, and reved great. To start with, then more / different issues, i will start a new thread!

[cre]

<dramatic mad scientist voice> Curse you BT!!!!! Curse you!!!

[btwilson86]

Lol Yes!!!! My diagnosis wins!




Well, at least until we read what Carl's other problems are :/