PapaChulos4U

Okay guys, I have not posted any updates about my truck in a few months because, quite frankly, it's about to go to the shredder.

List of new parts:
-BRAND NEW ATK crate motor
-NEW Alternator
-NEW Battery
-NEW wiring harness
-NEW TPS (tested; within spec)
-NEW Exhaust (downpipe to muffler, including O2 sensor)
-NEW Coolant Temperature Sensor
-Rebuilt injectors
-Tested VAFM; within spec

OK, with all of that new, the truck fires only when the temperature is above 70, idles SUPER high at about 2K (I took the AAV off and cleaned it, even bypassed through the throttle body; no change), then when the truck "idles down" it lopes/surges. When it's running, the throttle is ok, then backfires at around 4K RPM.

I seriously need to figure out how to fix this thing. I'm really about to sell it at a loss of about $4K. It breaks my heart, but nothing seems to fix it.

Oh yeah, it throws no codes, but the CEL stays on even after clearing the codes. There is also a sizzling sound that comes from the charcoal canister.

Any help?

Black_1985_SR5

iTrader: (1)

Tps, Afm, have you checked it the ecu is any good? New parts can be bad sometimes

snobdds

Start simple.

An engine needs: Air, fuel, spark, and compression

1. Air: AFM may be in spec, but is the flapper in it good? Is there any cracks in the intake piping going to the TB? No vacuum leaks?
2. Fuel: Is your fuel pump producing at a high enough pressure? Is the fuel damper good? Is your fuel pressure regulator good? Is there vacuum going to the FPR? Is your VSV for the FPR good? Is your cold start injector working? Is the cold start injector time switch working? Are your fuel injectors properly grounded?
3. Spark: Do you have strong spark? Is your ignition timing set correctly?
4. Compression: What are your compression numbers?

Report back...

scope103

Is the CSI connected? (The mixture might need to be rich-ened at lower temperatures.)

Is the CEL on solid all the time? How do you know there are "no" codes if the CEL is on solid?

wyoming9

iTrader: (1)

If all else is correct this in a rebuilt or new engine??

Do all the sensors and the ecu belong together not a mis match of crap from different years.

All vacuum hoses new and on correct .

Are all the fuel lines and filter new .

You did drop the tank pull the fuel pump bracket put in a new pump for the new /Engine.

I live North of you and my AAV has been disconnected for years .

I am leaning toward two things bad gas or filter something in the fuel supply system

The second being Vacuum hoses either bad or on wrong or both it is not hard to do.

I did offer in the past to come help you get this going you never got back*** I am now going into hibernation till the first hard frost.

I will pay you scrap price maybe a little more I Can come get it this weekend if your serious!!

snobdds

If you took off your AAV, how do you keep the venturi in the throttle body from icing up in cold weather?

Team420

^^THIS^^

I would pay special attention to #'s 3 & 4

Fordless

Backfires almost always mean some sort of timing issue.

boxer.fan

x2 timing

PapaChulos4U

OK guys,

1. The timing is perfect. We even installed a new chain when the motor had less than 50 miles on it because it was running so poorly.

2. The TPS is within spec (this is the third one that has been put on it). When it is disconnected, it revs to about 3K.

3. The fuel pump has been replaced on the truck as well as the strainer (not sure why I didn't include this before).

4. Compression is as follows: 1-169; 2-169; 3-170; 4-168

5. All of the parts are for a '93 pickup; I went to great lengths to ensure this was the case.

6. It may need a new Cold-Start Injector, but the temp has been above 80 here for over a week, so it shouldn't really need that anyway.

7. Vacuum lines are connected per the under-the-hood diagram.

My bad for not getting back to you before. I'm so pi$$ed at this thing that I can't see straight. And I'm not coming off of it for scrap money; I'll part it out first haha.

Thanks guys.

wyoming9

iTrader: (1)

Well one does worry when one says it is going to the crushers!!!!

slo6i

Im assuming you checked plugs cap rotor?
Drained the evap canister per the manual, made sure the pcv and associated emissions valves were operational and not leaking or plugged?
Tested coil and igniter?
Swap in a known good ecu?
Does it have good gas in the tank?
Make sure that the CEL circuit isnt shorting out hence why it is on?

Do you have the service manual for your truck? I would start checking all my resistances in the various components having to do with ignition.

bob200587

Take it to a pro.

Teuf

Subscribed, this needs a good ending.

PapaChulos4U

I just drained the EVAP system this afternoon. The coil is in good shape. I haven't swapped out the ECU yet because I can't find one that matches with the 3-connectors. I've been scavenging eBay for months and talked to many people, but nothing (so far at least). Gas is good, as is the PCV valve, cap and rotor.

PapaChulos4U

Anything? I think I may drop the tank again and take a look at the fuel pump. Maybe it's a bad one...

slo6i

Nevermind. Looked on profile.

Look up your ecu on car-part.com. They have a page of results for a 93 truck 4wd MT (federal emissions not ca)

Also, do you have the FSM for your truck? I can send you the ignition diagnostics page if you'd like.

snobdds

Just turn it on manualy and see first if it is working. You jump two terminals in the diagnosis box, but I forgot what two they are. Search on 4crawler's site to get the specifics or google it.

If you have the pump coming on then check the fuel pressure at the rail. It should be around 45 psi. If you don't have the tool, rent one from a local auto parts store.

These are better options then dropping the fuel tank and not being able to test anything.

PapaChulos4U

It's the Fp to +B terminals to manually start the pump. The fuel pressure is at 38 PSI, which is the extreme low-end of the spectrum but within the FSM specs. I just took it to yet another retired Toyota mechanic. I'll give you guys updates when I hear more.

PapaChulos4U

So, I just got the truck back. Turns out the TPS (#3 to be exact) was bad, so I had to get yet another one (another $100 to Autozone; I plan to return the other). Also, the TVV was bad, as well as the vacuum modulator. Luckily, the guy had a friend who had a 22RE and got those parts for free. NOW the speedometer does not want to work. I took the gear out of the transfer case and when you spin it by hand the speedo turns, yet when it's reconnected, nothing happens. The sensor is getting 12V and the readings seem to match the post here:

https://www.yotatech.com/forums/f116...16/index2.html

What do I do now?