1stoyota

I'm heading out to run a few cold tests:
-cold start switch/cold start injector (not relevant to this issues, but to the truck overall)
-Temp sensor resistance (3 points should follow the curve in the Haynes. I have 2 already)

Then I'll do another check for vacuum leaks. Does anyone have a good, relevant, diagram or photo of a stock '87. I don't trust what the POs have done, so I'd like to compare it with a known correct example.

After that I'm thinking that I'll drop the fuel tank to see if the Fuel Pump filter is clogged, or possibly test the pump's output (I have not looked at the FSM or Haynes for that test yet). While I'm there is there any "fix" for the fuel level sending unit?

That should get me started.

thook

If the high idle is consistent and does not drop off once the motor is warm, I'd start looking for a good vacuum leak somewhere. It seems to me it would also throw a code for the fuel/air mix, but maybe not.

I've never really had luck with a propane torch. Hopefully, you will. But, if not, see if you can find a mechanic with a smoke machine. I'm not sure what they're properly called, but I've had one used on my vehicle and found the big ass leak I could not find at the cold start injector.

1stoyota

The high idle doesn't drop off when warm, but only when placed under load by the A/C. I'm wondering if the AAV is always activated. I'll check that, too.

Speaking of codes. My apologies to you all for not giving them to you. It seems to be throwing a code 9 and 11:
9- Vehicle speed sensor circuit- this may explain the non-working cruise
11- A/C switch, A/C Amp, TPS circuit, neutral start switch- That's such a huge list with varying consequences that I'm not certin where to start.

abecedarian

I think that code 11 may be a left over from running with the disconnected TPS. Unless you cleared your codes by removing the EFI fuse in the cab or disconnecting the battery for a few minutes that is.

1stoyota

hmm. That would be nice. Thanks for pointing that out. I had missed it....

A few data points:

TSP tested- seemed to PASS
From VTA->E2 while throttle was closed =.66kOhm. Haynes says it should fall .2-.8kOhm. Guess that's a pass
From VTA->E2 while throttle was fully open =5.1kOhm. Haynes says it should fall 3.3-10kOhm. Guess that's a pass
From VCC->E2 while throttle was fully open =6.8kOhm. Haynes says it should fall 3-7kOhm. Guess that's a pass

At various temps I have tested the Cold Start and Temp Sender- both seemed to PASS
Water Temp; Cold Start Resistance; Temp Sender Resistance
70F; 40 Ohm; 1.9 kOhm
75F; 42 Ohm; 1.5 kOhm
90F; 54 Ohm; 1.4 kOhm
175F; 56 Ohm; .35kOhm

AAV pinch test seemed to indicate the AAV is functioning

Someone asked about ability to rev freely without load.
At WOT just before an indicated 4500RPM the motor cuts out, but at just less than WOT, the motor revs freely past 5000RPM.

I believe this would indicate that it's not a Fuel issue (someone tell me if I'm wrong) since it happens at about the same RPM in any gear I've tried, and under any load circumstances.

I just found a "Fuel Cut RPM" test in the FSM. I'll go test that then reset the codes and go for a drive.

1stoyota

I'm not sure what it means, but it cycled from 1600-1900 instead of the 1800-2130 that the FSM indicates.

Off to drive to see if the codes return....

Jay351

Are you sure your exhaust is not blocked in anyway... an old catalytic converter perhaps? Your 22re should rev freely past 5000rpm.

1stoyota

At this point I'm sure of very little. The truck is new to me and has held many surprises. I can say that at idle there are distinct exhaust pulses at the tail pipe. And I can't find a cat. It looks like it was replaced by a cheap muffler some time ago.

After about 15 miles, there are no new codes when jumping the diagnostic ports.

JDMSLIK

Buddy makes a good point here. You can check it with a timing light pretty easy. Usually you'll be off a ton and it'll start to run good if you crank your diz to the max in either direction.

I don't know about that cat one though. In my experience a clogged cat is ussually a boggy lack of power. Where a fuel issue is ussually a violent erratic misfire. I've been wrong before though.

I'd probably do a quick timing check. Then I'd probably really look into that fuel system. Fuel pumps can go really weird. You can have good pressure but no flow and have good flow but no pressure.
I had a similar diagnosis last saturday. A lady came in with a CEL light on, misfire codes all the way around. On the test drive it ran great, unless you booted it. At 4000 rpm a slight misfire occured and got worse the higher the rpms accelled. At a stand still it would do the same thing unless you gently pushed the accelerator, then it ran fine. I did a pressure check and it went fine, like 30 something psi. Then I pulled a fuel line off and pointed it in a container, it barely burped the gas out, no flow. The weird thing is we replaced the pump just under a year ago, so luckily it was still covered under warranty.

The fuel filter wasn't clogged so we replaced the pump. The client was from a small town and we found out she was filling up at a small private gas station. We went over the installation and didn't find any bent or clogged lines so we figure she got conned into some contaminated gas.

Another easy check you can do is sqeeze the fuel return line with some pliers while revving the motor. If it revs without hesitation, I'd definitely look closer at your fuel system.

JDMSLIK

Also get that intake elbow taken care of. Even if you gotta throw some duct tape on just to diagnose it. It could really throw your sensors off.

abecedarian

And I feel stupid- verify valve adjustments are proper as well.
engine warmed up: .008" intake / .012" exhaust
loose valves will affect the flow of the engine also.

1stoyota

One of the last things I did tonight was to check/set the timing. It started at about 12*, so I reduced it to 5* per the sticker under the hood. Of course the idle dropped, but it made me notice that it idles normal with the test jumper installed, but idles up around 1200 with it removed. I guess I should stick to one problem at a time unless they are related...

The dizzy is nearly maxed out at the "top" of the adjustment slot to get down to 5*. In fact, it may be maxed out there. I don't recall. Are you saying that if it runs good at the "bottom" of the slot, then there's a good chance that the cam/crank timing is off?

I'll try the pinched return tomorrow and report back.

I didn't actually drop the tank as I said I would since hitting the same RPM caused the same problem under no load. I guess I can still do that, but this timing/valve issue sounds plausible.

It had duct tape on it that I didn't trust. I wrapped it with electrical tape so I could get into all of the accordian valleys well. I don't believe I have a vacuum leak there, but I do want to replace it. Does this forum have a decent dealer they can recommend?

I guess it's time to get those feeler gauges and a new valve cover gasket....

Thanks for keeping up with this, guys!

JDMSLIK

A coupel weeks ago I ws doing a t-belt side job for this lady I know. After the job, it idled and ran fine but pinged like crazy when give'n'er up a hill or just taking off fast. I did a timing check and I was at like 24 btdc or so. I cranked the diz to the max and managed to get it to 15 btdc and it ran fine, no pinging. I pulled the timing cover again and realized there were 2 sets of timing marks, one for a 2e and one for a 3e. Needless to say I was off a tooth. Which was weird cause every other time I've been off it's run like crap, but this one was just pinging and still had tercel like power.
My point is your off a tooth sometimes adjusting the diz can help it to run better and verify an off tooth problem.

abecedarian

I adjust the idle speed with the test connector unjumpered.
I'd guess that if you're having to twist the dist against the bolt to get the timing retarded enough that something is definitely amiss. That implies that the cam may be advanced. That made me rethink what I wrote earlier about the cam being retarded and made me feel retarded. So I googled a bit and confirmed an advanced cam will move the powerband down and a retarded cam will move it up in the RPM's so I was backwards. So this kind of goes with your situation- good power down low, lack of power up high and distrib nearly maxed out for proper timing.
No particular dealer I'd recommend, but you should be able to find a usable piece in a dismantler / wrecking yard for quite a reasonable price.Good Luck!!!!

thook

Check cjcolson or DeathCougar (Nix99) for that intake tube. Or, if neither of them, dirtoyboy.

1stoyota

I didn't make time today to pull the timing cover since it looks like that'll be the only way to check the relationship of the crank to cam. I guess I'll round up a chain and tensioner et. al. and plan on replacing them while I'm in there. If there is another way to check (like just pulling the valve cover gasket) I can try one evening this week. Would that be practical/useful?

I would worry about driving it this week, but who knows how long it has been like this and whatever damage is likely done....

I did pinch the fuel return hose and found no change. WOT it still falls on its face at 4500, but at 95% throttle it'll pull beyond. I filled the tank yesterday so I didn't drop it on the off chance that I'll see something on the pump end. I'm driving it this week, so the tank should be empty on Saturday. I'll pull a fuel line one evening this week as a quick test.

BTW- My passenger power window hasn't worked since I bought the truck. It came with a replacement pax switch, but that didn't help (anybody need one, it's barely used? PM me). Yesterday the driver's side quit working. I found that there was no power on the Blue/Red wire at either door. I jumpered the Black/Yellow to the Blue/Red at the Power Window Main Relay (behind the ECU). Of course that gets the Driver's side working, but the Pax side still dpes not. Does that sound like a failed main switch (in the driver's door), or a failed Power Window Main Relay, or both?

Also, it doesn't want to start when the air/water temps are in the upper 80s (or even in the upper 70s, but it catches on the second try then). I'm guessing the cold start switch is marginal and that's why one of the POs installed the momentary switch to activate the CS Injector. Anybody know if the ECU just looks for a < or > resistance to activate the injector, or if it uses the resistance to determine a pulse for a metered amount of fuel?

Thanks again for all the help!

1stoyota

The problem remains, but I have ruled out a few more items and have some photos that may be helpful.

I've replaced the cracked intake elbow. No change in idle or power issue.

I adjusted the valve lash. But I potentially made things worse. I can't hear it now, but immediately after making the adjustment I could hear slight valve clatter where I could not hear it before. While I was in there I took a couple of photos to determine if I have a timing issue. The first photo is TDC Exhaust stroke for piston 1. The second photo is TDC Compression stroke for piston 1.

Am I a tooth or two off, or is that my imagination? (FYI- the chain tensioner doesn't appear overly extended so I think the chain is fairly new though it has plastic guides)

Another unusual symptom: Under normal conditions (city driving while not towing) I don't seem to be using much oil. Under Highway or load (such as towing a small utility trailer w/ lumber), I used almost 1/2 of a quart in 75 miles. The plugs are clean and the oil is coming out under the vehicle. It doesn't appear to be coming out of the dipstick tube like excessive blowby. Any ideas?

1stoyota

I meant to add that I did a compression check. I need a redo as I forgot to prop the throttle open, leave all the other plugs out, and it was not very warm. So the actual numbers may be useless, but the comparisons may be useful.

1- 150
2- 135
3- 130
4- 135

I think my poor testing procedure can account for some of the low numbers, but 20 PSI difference seems extreme. However if my cam timing is off...

After looking in Haynes and the FSM there are only references to bright links on the chain, and nothing about the cam being oriented vertically when the crank is oriented for the #1 piston at TDC. So I guess my photos aren't helpful. Will I need to replace the newish chain to get things clocked/timed correctly? I was hoping to avoid that if it is unnecessary.

If anyone can learn anything from these photos, or I need to be focused on something else, please let me know. I've reused the old gasket so I can pull it again without any loss or repercussions. I'll put the new gasket on when I'm buttoning it up for a while.

Thanks!

Junkers88

I had a similar situation with the idle on my 86 and ran the gamut of things to check, just like you have. It turns out I had a vacuum leak where the intake attached to the head. The gasket was missing a piece. I found this out by running some seafoam through the motor and some of it leaked out of the gasket area.

All that work, time and money for a 3.15$ gasket.

So you've done the TPS, AFM, valve adjust, comp check etc..... You don't get anymore engine codes, it idles at about 800 with the jumper in and about 1200 with it out. I'd have to point to a vac leak and replace the intake gaskets. It only takes a few minutes and it'll eliminate one possible problem area.

Keep us informed.

1stoyota

Well, you caught me. You also reminded me of a test that I had not conducted. I had not checked the AFM, yet. Yesterday I did the Haynes check and it failed one of the 4 resistance tests shown on the chart. I'm not certain what the failure between pins E2 and VB should cause, but I'll need to get an AFM that tests good before going much further.

BTW- I have the gaskets you mentioned, and I hope to get to them Monday....

Thanks for the continued help!