u/Hefty_Extreme_30

This is a continuation of my "Horrible Hesitation" thread - https://www.reddit.com/r/ToyotaPickup/comments/1wxgt3p/horrible\_hesitation\_when\_punching\_throttle\_help/.

I did some more diagnostics this weekend:

- Ran a smoke machine - there was smoke coming out of one VSV and the EGR vacuum modulator. Not sure if that's enough of a leak to cause the problem. I disconnected and plugged the vacuum lines leading to these, and nothing changed.

- Tried a used (not necessarily "known good") AFM - no improvement. If anything, it hesitated even more. I suppose that could mean that it is in fact the AFM, but I'm not sure where to get a "known good" one, unless I try one of the aftermarket new ones?

- I got the fuel injectors out. Turns out they are not Bosch, but some Aisan brand injectors - 23250-XXXXX, so I'm guessing they were from some other application and rebuilt? I'll be putting in the remanufactured GB injectors once I receive some of the parts that I need.

Speaking of parts, can I reuse the connector in the last photo, or should I buy a set of new ones with pigtails? The broken ones seem to still grasp nicely to the injector, despite their looks.

In the meantime I'm going to get a new fuel filter just in case, new banjo fittings for the fuel lines, and maybe the new connectors.

I'm not super optimistic about the injectors, but at least that'll be something I'll be able to cross off my list.

As the video shows, I'm having a terrible hesitation in my '87 4Runner - the engine feels like it's about to stall when I give it quick gas. When applying throttle very gradually, it seems to rev up pretty well.

Here's what I've checked to date:

- Checked fuel pressure at rail - 40 psi at idle with vacuum removed, 30 psi at idle with vacuum applied. Fuel pressure does not drop when punching the throttle.

- TPS is fairly new Toyota unit (I performed all the FSM tests, all passed)

- I performed all the AFM tests in FSM, all passed. One small concern is that when I opened the flapper gradually, it did have one small resistance dropout at the nearly fully open position (which I'm thinking does not come into play when just giving it gas like this, but maybe I'm wrong)

- Replaced all vacuum hoses with OEM hoses

- Adjusted all valves to 0.007"/0.010".

I'm not sure where to look next. I'm almost to the point of checking wire continuity from AFM to ECU, or just replacing the ECU. But is there anything else I'm missing that I should look at?

As the pictures show, we have two valve manifolds on opposite sides of the house. The main water supply line is approximately in the middle of the two manifolds. I'm looking at two approaches for backflow prevention - one is to use a single DCVA near manifold A, with a connecting line running to manifold B; the other to install a separate DCVA near each manifold.

There's the obvious extra cost of the second DCVA and the additional fee for inspecting two rather than one DCVA. But it would be quite difficult to run a connecting line between the two manifolds - I have to route it through the crawlspace, through a semi finished basement, and through a finished room. So the two DCVA approach will be a lot easier to install.

Aside from complexity of running the pipe and cost, are there any other considerations I'm missing in deciding which way to go?