Jerry Dork
Oct. 21, 2013 2:06 p.m.

Here we are about 10 months later, still a problem.

1987 MR2 NA 4AGE now with manual fuel pressure regulator and new exhaust.

65-70 mph and after a fairly short time, hesitates and sputters. If I give it gas it mostly goes away, coast back to speed and it's back again. Street driving is fine, idles fine, starts every time.

So far: replaced TPS, fuel filter, plugs, wires, distributor, module, coil. Unplugged the O2 sensor and still did it so I plugged back in. Running 91 octane and fuel injector cleaner every fill-up. Still...

To try: IAT, EGR valve. Fuel pump? Now I'm just guessing.

I took some video w/ my GoPro on my way to an auction and back Saturday to at least show what it was doing. Didn't buck and hesitate as bad as usual (like jolting me pretty good) but you can definitely hear it. Youtube Especially near the end.

Oct. 21, 2013 2:27 p.m.

Vacuum leak?

marks93cobra New Reader
Oct. 21, 2013 3:28 p.m.

Check your engine and ECU grounds.

Perhaps get a manual fuel pressure gauge and zip-tie it to a wiper so you can keep an eye on it while driving.

carbon Reader
Oct. 21, 2013 3:31 p.m.

Ive seen swing door style toyota air flow meters do weird stuff. make sure it's not corroded inside. You will have to cut away the silicone around the black cover, then if everything is ok, resilicone it to keep it dry. (Fyi, you can do minor adjustments to afrs by changing the preload on the spring that closes the door )

Jerry Dork
Oct. 21, 2013 7:18 p.m.

In reply to carbon:

I'll give that a go this weekend. While I'm looking for vacuum leaks. What's the best way to find vacuum leaks? I know soapy water works for air leaking out, does it work for air leaking in?

doc_speeder Reader
Oct. 22, 2013 8:10 a.m.
carbon wrote: Ive seen swing door style toyota air flow meters do weird stuff. make sure it's not corroded inside. You will have to cut away the silicone around the black cover, then if everything is ok, resilicone it to keep it dry. (Fyi, you can do minor adjustments to afrs by changing the preload on the spring that closes the door )

+1 on this. I had a VW Digifant with the flapper air flow meter do EXACTLY this same thing. Replaced it with a used one from a wrecker and it cured it. For what it's worth, my old one looked perfect inside.

Oct. 22, 2013 8:35 a.m.
Jerry wrote: In reply to carbon: I'll give that a go this weekend. While I'm looking for vacuum leaks. What's the best way to find vacuum leaks? I know soapy water works for air leaking out, does it work for air leaking in?

Spray starting fluid on the lines, when/if idle rises, you've found your leak.

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