Andy A

94,4x4,SR5, 3VZE, 200,000 miles. Yotatechies could use your help/suggestions with some issues that I am now having after a head gasket teardown/rebuild.

For some background, passenger side head gasket was leaking coolant externally at cylinder #5 rear corner of block/heads. No coolant was present in the oil nor was there any oil present in the cooling system. No other issues with truck at the point of teardown except some not so great brakes and some oil leaks (mainly valve covers).

Issues I’m having now that were not present before teardown.

Issues after putting it back together.

1) Reoccurring code 71 (EGR), has happened numerous times
2) Reoccurring code 41 (TPS), has happened only 2 times
3) Terrible acceleration, it just doesn’t go. Half throttle, three quarter throttle, full throttle, it just feels dead/flat but it wants to go. Issue is not as pronounced when engine is cold. I am living the Castrol commercial except it ain’t sludge.

Solutions to rectify #’s 1,2, & 3

1) Throughly cleaned EGR, applied vacuum, diaphragm holds.
2) Got funny reading off TPS so replaced it. Had 200000 miles on it and I may have gotten carb cleaner on it when cleaning throttle body. Followed FSM and 4Crawler’s specs for new TPS. I am still going to go back sometime this weekend and do it again just to make sure I did not do something wrong.
3) Have no clue, possibly related to # 1 & 2 or something totally different?????

Items that were replaced or worked on.

1) Heads were taken to machine shop. New seals, valves reground, heads shaved, the usual stuff
2) New camshafts because of this problem with passenger side cam and
3) Timing belt
4) Idler # 2, #1 was good, tensioner good
5) Engnbldr gasket set
6) Engnbldr head bolts
7) Throttle body cleaned
8) Upper/lower intake manifold thoroughly cleaned. Huge amounts of carbon buildup.
9) New fuel injector connectors https://www.yotatech.com/forums/f128...s-3vze-218912/,
10) Fuel injector O rings, vibration insulators, grommets, screens, pintle caps
11) TVV repaired, although probably should have bought new one
12) NGK BKR5EYA plugs
13) Piston tops cleaned of carbon
14) New battery

Nothing else I can think of off the top of my head. Thanks for reading.

MudHippy

Yeah, my right camshaft has the same damage. I deemed replacement unnecessary. Haven't had any trouble with it yet. Probably been like that for who knows how long, was like that when I got the truck. Noticed it the first time I had the valve covers off to change out the gaskets for those which was 23,000+ miles ago.

O.k., so code 71. Did you clean out the outlet tube that feeds into the plenum chamber? It could be that or the EGR valve might be clogged up somewhere else. Maybe it's restricting gas flow causing the temp sensor to get a false reading. It could be the temp sensor or the VSV for the EGR valve needs replaced too. You should follow the procedure for "2 trip detection logic" to get a better idea as to what's going on there. Starting on FSM Page EG2-173 and continued on page EG2-181. http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf and/or test the temp sensor itself. Testing procedure found on FSM page EG1-214 here. http://personal.utulsa.edu/~nathan-b...43egrgaste.pdf To check the VSV see FSM pages EG2-150 & EG2-151 here.
http://personal.utulsa.edu/~nathan-b...77exhaustg.pdf

On the code 41 thing, you'll have to go through the post-diagnostic checklist on page EG2-188 of the FSM if the TPS adjustment is still good to go.
http://personal.utulsa.edu/~nathan-b...86troubles.pdf
A better reference for adjusting the TPS if you're not 100% on how is the FSM throttle body pages here. http://personal.utulsa.edu/~nathan-b...93throttle.pdf Another good read on the subject is this thread. https://www.yotatech.com/forums/f116...r-help-219947/

There's other ways to find out what the issue might be with the lack of power too. The FSM lists 20 areas, ranked according to possible likelyhood, to check if the trouble is "Hesitation/Poor acceleration". 1 being highest priority/likelyhood, 20 being lowest. Here's the pages, EG2-9 through EG2-11. http://personal.utulsa.edu/~nathan-b...63troubles.pdf

You might try rechecking 1-5 and then checking 6 and 7. 6 is the distributor. Check the air gap and the signal generator(pickup coil)resistance values that are listed here on FSM page IG-28. http://personal.utulsa.edu/~nathan-b...14services.pdf
Hint: It's recommended to use a non-ferrous feeler gauge to measure the air gap. Details on how to check the air gap and the resistance values are found on FSM page IG-23 here. http://personal.utulsa.edu/~nathan-b...12onvehicl.pdf

7 is compression. If all's checking out good with 1-6, get a compression gauge and check that. FSM page EG2-30. http://personal.utulsa.edu/~nathan-b...66compress.pdf If that's good enough...then go on to 8...you know the drill.

Entire 93 FSM for reference.

Good luck!

Sidenote: It's also important that you don't have any vacuum leaks. All possibilities of which aren't going to be covered in detail in the FSM, but could cause a driveability issue like the one you're describing too. I know from experience that simply rerouting one or more of the vacuum hoses on the intake plenum and/or connecting them to the wrong ports will cause the same sort of trouble. And would be alot harder to diagnose if it were so.

Andy A

Thanks for the reply Mudhippy, looks like lots of things to check into.

Kind of weird on those camshafts, I replaced because I was worried about it eating into the bearing cap. Good to know yours is holding up in that respect. I think mine had been that way for a long time also because if it had been recent the breaks would have been shiney.

When the check engine light comes on it does so only temp, usually less than a minute then goes back off, it never just stays on.

Yes cleaned out the EGR outlet tube and every other tube that was in the upper intake. I was really suprised as to the amount of carbon that had built up in the course of 16 years. I even pulled the plugs on the upper chamber to try and clean that out the best I could and replaced them with toyota plugs. Question should not the EGR get hottttt I mean to the burn finger stage? After driving a bit and shutting down it is hot but not the burning finger hot. I'm assuming valve lash can effect EGR temps also???? Although the machine shop did set the valve lash I still wish I had gone over all of them before I reinstalled the heads as I think they are still a little loose. To my ears there is just to much chatter, but better loose than to tight.


Do you think it is possible to be 1 tooth off on the distributer and the motor still run some what decently???

Thanks for all the links to check, your just trying to making it easy

Yesterday morn I was checking out that chart, and I find it interesting that #4 is EGR, 1-3 do not really seem to apply in my case. I will have to go through the rest of them. I guess I was hoping for a silver bullet you know what I mean

No vacuum leaks that I know of, and was sure to takes many pictures of all the lines prior to teardown so I had a good reference.

There are some other misc parts that I still need to replace as $$$ allow, one being the fuel filter as it has never been replaced since I bought the truck new in 94. My main objective right now is to get the thing back running decently as I have to change the timing belt on our 300(long overdue still original 94) and need to have dependable transportation in the mean time, doesn't have to be perfect just dependable.

PS the line you edited about no coolant in the cooling system, kind of funny because in some ways that was correct and was how I found out there was an issue with the head gaskets. Was driving home from work in the morning and the temp gauge started to climb, luckly it never got to the red, but when I got home I checked the cooling system and it was mostly shall I say, no coolant in the cooling system.

MudHippy

1.The EGR valve body doesn't get so hot as to cause a burnt finger. The inlet tube between it and the exhaust manifold might though. Depends on how thick of skin you've got I guess. But, it does/should get really hot to the touch. If not, perhaps it's clogged partially and not allowing proper exhaust gas flow to the EGR valve. And I don't think valve lash could effect the exhaust temps enough to notice, or for the sensor to catch it. I'd trust for now that they're set correctly. I've had mine to loose and after fixing them noticed no change in the amount of noise coming from them(which I'm not sure I could ever hear to begin with). That and the fact that valve clearance ranks 16th on the list for causes of hesitation/poor acceleration.

2. The 2 trip detection logic test mode is a complicated procedure and can detect only certain EGR system malfunctions. Those are a short in the VSV circuit, the EGR valve sticking/stuck, or it's not being opened due to vacuum loss in one or more of the hoses leading to it or the vacuum modulator. The only one of those not diagnosable in others ways is the EGR valve being stuck open, or to put it another way not closing fully when it should. What I'd guess would be the case is that it may be not able to close fully or as much as it should be at certain times. It should be fully open, fully closed, or somewhere in between depending on engine conditions. I know you said you cleaned it, but depending on how well, it could still be malfunctioning to some degree. And it's possible that by attempting to clean it you may have caused some of the deposits to become lodged in the valve and cause it to stick open or be unable to close fully. I'm highly suspicious that could be the case because of the problem arising after you cleaned it and having not been present proir to doing so. To better understand how/why that could be causing the problem here's another link. http://www.autoshop101.com/forms/h61.pdf And for a clearer instruction on how to perform the 2 trip detection logic a.k.a. diagnostic TEST mode see here. http://www.autoshop101.com/forms/h27.pdf

3.I'd say no on the distributor being off a tooth. You wouldn't likely be able to get the ignition timing set correctly if it were. I could be wrong, but I'd start with the full check of the EGR system before moving on to that.

Andy A

It wasn't until after I got the motor back together, it started throwing the code 71 then I took just the EGR valve off and cleaned it hoping that would remedy the situation, everything else was cleaned prior. I am fairly sure the EGR valve is good because if you apply vacuum to it, it holds and I tried as best I could to check the motion of the plunger inside and it appeared to go through it's full range of motion. It also when closed did not allow any cleaning fluid to pass thru it and when open cleaning fluid passed freely.
Going to test the VSV and hopefully the modulator today have got to dig up a vac gauge from somewhere.. The sensor I'm not sure I will be able to test, not sure I have anyway of heating oil up to the required temps to test the resistance on it. another thing I thought of was that maybe a dirt dobber got in one of the vac lines and clogged it up, I have had that one happen to me before with other vehicles.

On a good note so far no more code 41's after a little bit of tweaking.

Again thanks for all the tips and suggestions Mud Hippy, hopefully I will get it figured out. Quite possibly I'll get lucky and the EGR malfunction is somehow tied to the acceleration problem.

Andy A

Dang old dirt dobber's, kill the dirt dobber's one had got down into the vac line that pulls on the EGR and clogged it so the EGR was never pulling any vacuum. Need to take her for a drive now and see what is up. After first drive soooooo much better so far, keeping my fingers crossed.

At least now I know how to test the VSV, which tested good.
Hooking 12v across terminals and blowing thru E air came out thru filter.
Unhooking 12v source and blowing thru E air came out thru G.
No continuity between either terminal and VSV body.

Tested sensor, thank you candy thermometers
@ 122F = 69K ohms right on the margin,
@ 212F =13K ohms right in the middle,
@ 302F 3K ohms right in the middle.

For the modulator plugging P & R and blowing thru Q air came out thru filter.