1989 mr2 4age [engine](/topics-engine-toyota/) no respons...


1989 mr2 4age [engine](/topics-engine-toyota/) no response from throttle body Mechanic's Assistant: How many miles are on the Toyota? Is it an automatic or a manual transmission? Manual tranny, 200k, fresh rebuild of ever...

1989 mr2 4age [engine](/topics-engine-toyota/) no response from throttle body Mechanic's Assistant: How many miles are on the Toyota? Is it an automatic or a manual transmission? Manual tranny, 200k, fresh rebuild of everything Mechanic's Assistant: Are you fixing your MR2 yourself? What have you tried so far? Starts no problem, idles at 700 or so, and i adjusted the TPS but still no response when I open the throttle plate by hand

Automotive Expert
Hello. Welcome to Just Answer. I am very sorry that you are having is frustration,. Please allow me to assist you. Before we begin, can you please explain the issue a bit more? If I understand you correctly, manually moving the throttle arm does not increase the RPM., Is this correct? Also, is the Check Engine light illuminate don the instrument panel? Thanks!

That is correct and the check engine light is off but comes on if I disconnect the TPS.
Automotive Expert
Does anything happen with regard to the engine running when you move the throttle plate (to mimic pressing on the accelerator pedal)?

It revs up maybe 100 rpms but that's it.
Automotive Expert
Without looking at this in person, this sounds very much like you have a vacuum leak someplace on the engine tubing, or, a [timing belt](/topics-timing-belt-toyota/) issue. On this vehicle, when you open the throttle plate, all you are doing is admitting more air into the engine. If there is a crack in the tube between the air flow meter and the intake, you will get exactly what you are having. Also, any amount of other air leaks (vacuum hoses, power [brake](/topics-brake-toyota/) booster hose, etc) will also give you this condition. Usually, if the engine does not increase in RPM it is getting to much air. If all of the vacuum lines are good and solid, the other possibility may be your timing belt has stretched and the cam timing is off 1 or 2 teeth. This too will give you the issue you are experiencing. If the check engine light is off, and it comes on whilst disconnecting the TPS\< we can say all of the engine sensors are good. This leaves the issue to be a Mechanical problem. IE Timing belt of massive vacuum leak. Could also be a leaking intake manifold gasket, throttle body gasket, a stuck open EGR valve, a lot of possibilities, I am sorry to say.

It's a brand new timing belt, and I just finished the rebuild so I doubt it's that... New bearings, pistons, seals, vacuum lines, clutch, gaskets, and it was right at TDC yesterday when I installed the distributor, pointed to #1. I have no problem getting it to start and turn over but the cold idle is low and I cannot rev the engine at all. Just about every single thing was hand cleaned on this engine including the egr as well
Automotive Expert
Do you have a vacuum gauge? This will be of great benefit to see if we have a vacuum leak.

No I don't but I sprayed [starter](/topics-starter-toyota/) fluid on all the hoses and connectors and didn't hear or feel any change
Automotive Expert
This engine's fuel injection system is based on the Bosch L-Jetronic system. If it will not rev up I am thinking it is getting too much air; and that is what the L-Jetronic meters. A quick thing to check: See if the air flow meter flapper door is stuck open. If the spring on the AFM has failed, it will not send the proper information to the computer.

Okay I'm checking that now
Automotive Expert
Is this a 16 valve or a 20 valve 4A engine?

16v4age
Automotive Expert
If the AFM is OK, I would be looking at your cam timing again.

Customer attachment 2/7/2021 11:34:53 PM
Automotive Expert
Thank you. Pull the front boot off an see if the throttle plate is actually opening.

I did and it immediately stalled. The mass airflow meter is below the elbow boot
Automotive Expert
Yes but is the throttle plate flap actually moving when you manipulate the throttle shaft arm?

it is
Automotive Expert
The fact that it stalls with the boot off is to be expected. Let's check this next: look to see if your vacuum advance line to the distributor is ok, and then check the plate to see if the advance mechanism is moving with regard to vacuum applied. If this engine has vacuum advance AND vacuum retard, you may have the lines backward. This may be a seized advance unit in the distributor. Weird but possible.

The distributor doesn't have any vacuum lines attached to it. There are two plugs that plug into the wiring harness and then ignitor but no vacuum lines that I can tell
Automotive Expert
Or the advance diaphragm is bad. Oh. Ok.

The distributor is adjusted via two bolts on the sides of it
Automotive Expert
This takes us back to rechecking the cam timing.

I'll do that. Give me a few minutes
Automotive Expert
Make sure the cam timing is not 180 degrees out. This is something that may be pertinent also...What is your fuel pressure? It needs to be 30 PSI at the rail. One more thing that just came to mind. Does this engine have the dual plane intake system? If it does, and the flaps are open, the engine will not rev. Sorry about the suggestions one after another...Its been about 10 years since we had a 89 MR2 in the shop for anything. They are rare these day. I cannot remember if it has a dual plane or intake or not.

Turning the engine to TDC and checking the cam marks on the sprockets show that they're both lined up. As well as a mark on the crank sprocket behind the harmonic balancer lined up. It's at TDC
Automotive Expert
One more thing that just came to mind. Does this engine have the dual plane intake system? If it does, and the flaps are open, the engine will not rev.

Not sure what the fuel pressure is, there's only a small vacuum line running to the fuel regulator. There is a dual plane intake, it's called the TVIS (toyota variable intake system) I'll check the vacuum lines running to it tooI'll check it.
Automotive Expert
Yes, the TVIS. Need to make sure the plenum flaps are closed at idle. If the TVIS is messed up, that would explain the air issue. Note that vacuum closes the TVIS.

Im checking the vacuum lines to it but it's currently hot so it's difficult to get my arm up in there. I'll keep you posted
Automotive Expert
Let it cool off completely. No need to get burnt. Let's pick this up again tomorrow. I will be on line at 2;30 PM East Coast time. OK?

Sounds good to me. Thank you. My name is \*\*\*\*\* \*\*\*\*\* the way
Automotive Expert
Excellent. Nice to meet you Sir. I will talk to you tomorrow. Have a great evening.

Hi I just adjusted the distributor timing and it caused the car to rev and idle higher and it turns out the distributor needed to be timed at 10° before top dead center
Automotive Expert
That is good to hear. That was going to be my next question to you when you came back online. Glad to hear you have it sorted out!

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