irish_tyrant

Hi all, I've been searching this for 2 weeks now and I have found people with a similar problem but their solutions didn't help me. Instead of thread jacking, here's my issue.

I got a "super stock" 3vze from Oregon Engine Rebuilders about a month ago. I spent 2 weeks pulling my old motor, swapping over the needed components and reinstalling it. I fired it up 2 weeks ago and it seems to run ok. It idled at 1100 rpm and warmed up nicely. As it warmed up though, the idle got rougher. When its at normal operating temp, it runs at about 500 rpm and then eventually stalls.

I have timed it to 10 deg BTDC, checked the VAF (MAF), Throttle Body, Cold Start Injector per the FSM with my trusty multimeter and they all seem fine. I have hosed carb cleaner all over the place but found no vacuum leaks. I'm not getting any codes either.

I'm all out of ideas and ready to take it to the shop with a blank check as it's getting frustrating. I want to break this motor in but I'm worried that if it's not running right, I may be doing more harm than good.

Any suggestions as to what it may be?

The truck is a 1992 4Runner, 3.0, trans was an auto but I swapped it to a manual about a year ago.

Any help is appreciated.

93toyrunner2

Did you have the injectors cleaned? Have you unplugged the TPS to see if it helps? Have you adjusted the idle screw on the side of the throttle body? Have you checked for codes? Did you use the correct ngk spark plugs and ngk wires? Did you set the timing with the jumper in the diagnostic ports? Is the timing stable or jumpy when you are looking at it with timing light?

irish_tyrant

I didn't think to clean the injectors while they were out but I ran techron fuel system cleaner every 5000kms in the old motor and the injectors seemed clean when I swapped them over. I haven't unplugged the TPS yet, I'll try that today. I adjusted the throttle body screw to the proper resistances per the FSM. Idle screw a different deal? No codes. I just put new plugs in, Bosch super plus. All they had at the time. I was going to change them at 10000kms and figured they'd be fine until then. New NGK wires last year. Timing was set with the jumper in. I had to set it at 1000rpm because when it warms up and drops to 750/800 the idle is rough and the timing mark gets jumpy. I figured I'd dial the timing in after I get the idle smoothed out. I don't think the timing is the issue.

jbtvt

What throttle body screw adjusts to resistance aside from the TPS? Can you tell if it a mix issue, ie running rich or lean? I would strongly suspect the ECT/air in coolant system. Also get a vacuum reading.

irish_tyrant

UPDATE:

So I fired it up, 1300 RPM. As I drove it into the garage, it would want to bog down alot while under load. Let it warm up. was at about 1000 RPM at this time. Pulled the TPS plug off and it reved up to about 1300 RPM again. Is that what it should do?? Plugged it back in and it dropped back down to 1000. At normal op temp, it was at about 800 rpm but rough.

Pulled the intake and MAF off and hosed the throttle body with cleaner. Sprayed the MAF too but it was pretty clean. Lots of gunk came out of the throttle body though but I don't think that was a cause of this problem.

For the idle screw, I unplugged the TPS and checked that the resistances met the FSM limits. I put the feeler gauge in between the screw and stop in the first pic. (not sure if it will show up properly)

There are also screws behind the dashpot, and beside it (circled on the second pic) and another at the top of the throttle body by the intake chamber. Do I adjust these too?

In the first pic you can see a tee with a white cap on my upper heater hose. I left this off when I filled the coolant so that air would push out here. I then ran the motor with the rad cap off and topped up as the coolant circulated. If its air in the coolant, I don't know what else I can do to purge it.

Also, the long hose coming off the TPS is just for me to apply vacuum to. The FSM says to apply vacuum to the TPS, then unplug it, then put a 0.2 mm feeler in between the screw and plate but it shows the feeler going to the screw on the left (towards front of vehicle) screw and I dont think a feeler will fit in there. So did I check the TPS correctly?

irish_tyrant

Forgot to mention, I pulled the vacuum hose of the top of the EGR while running. There was a slight change in the motor but it was slightly worse. Also, I don't have a vacuum tester so if I buy one, where do I check the vacuum and how much should I see? And I dont know if its running rich or lean. Doesn't seem like either, just rough.

irish_tyrant

All plugs are getting spark. Idle adjustment screw on top of TB by the intake chamber didn't yield any improvements. It idles at 800 when warm but is still rough. Almost feels like one cylinder is missing.

irish_tyrant

I'm trading in my Bosch Stuper Plus plugs tomorrow for NGK platinum's just in case. I can't imagine that Bosch plugs suck so much that the run like crap brand new. I'm also putting a new cap and rotor to eliminate that as well.

I held the idle at 2500rpm for 90 sec per FSM before adjusting the idle screw and it felt like it was stumbling at the high rpms too.

The thing that bugs me is that most of these parts came off my old motor and it ran fine when I pulled it. Nothing should have changed or broke so I can't figure why one of the reused components would be the culprit.

Thanks for the replies so far, I know no one wants to spend their Sunday on the forums.

jbtvt

Good thread on burping - https://www.yotatech.com/forums/f116...-flush-110753/

ECT= Engine coolant temp sensor, half under the intake manifold by the firewall. resistance specs are in the FSM.

Your o2 can also cause poor closed loop performance, but that should make it run noticeably rich.

irish_tyrant

Soo, I jacked the truck up and burped the rad. I got some air out of it and it seemed to run a bit smoother so I figured I'd take it for a drive. It had a huge bog down when applying gas in second and I got the CEL within the first minute. Codes 41 (TPS) and 52 (knock sensor).

Question 1: can I check and adjust the TPS properly without removing it?

Question 2: I replaced the knock sensor when I did the motor. Can I check the wires/resistance or something without removing the intake again??

Thanks

jbtvt

Codes are good. I'd think you would need to be way off adjustment to get no VTA signal, but I'm not familiar with fixing either code fortunately, so readjustment is worth a shot. Read through 4crawler's page on how the ECU see the TPS signal, and adjustment procedures. I don't understand what you were saying with how you adjusted yours with the feeler earlier, his page will clear it up though.

https://www.yotatech.com/forums/f116...thread-216933/ is the go to code 52 thread. I doubt you can do anything without pulling the intake.

93toyrunner2

1: Yes. I grabbed a spare TPS connector and 8 inches of the wiring at the pull yard. I use this to clip in and set the TPS, then remove it when it is set.
2: Not really. You can test the wiring resistance from the connector back to the ECM in the pass side kick panel. Check the FSM (link in my signature)
Did you install an OEM sensor, or one from the auto parts? Did you replace the pigtail with the OEM one, or reuse the original? Brittle wiring in that area can cause the signal to be lost, and thus cause the code 51 and bogging down. Try to disconnect it and reconnect it to see if it clears it up. Don't forget to pull the EFI fuse to clear the code out first.

irish_tyrant

I'm going to adjust the TPS this weekend. I'm wondering if the code 52 is legit or if its throwing that for some other reason. I really dont want to pull the top end apart again. I used a new knock sensor but not OEM. Also, I didn't replace the pigtail. In hindsight, I really wish I had but it looked to be in decent shape. Are non-OEM knock sensors that bad? It seems like a simple part.

Bob, how do you get the feeler gauge under the spring assy to setup the TPS without removing it? I have a few pieces of wire that I used with small female spade connectors to go into the TPS so I could get them with the multimeter but I cant fit the feeler gauge into the spot between the adjusting screw and plate.

irish_tyrant

Also, where is the best place to hook in the vacuum gauge and how much should I see? I can't find anything in the FSM or on the forums that actually show how to check vacuum leaks this way.

Thanks,

93toyrunner2

I have a set of feeler gauges that are lazy L shaped, and I can slip the smaller part of the gauge in without too much trouble. I do have the two gauges removed from the stack to make it easier.

93toyrunner2

Here is a good guide to assist with the vacuum routing. Check your routing of hoses, then use carb cleaner and spray all over the hoses while the engine is running, listening for a change in idle.

93toyrunner2

Random thought: Did you clean out the carbon in the upper intake plenum before you put it on the motor? What about the carbon built up in the EGR tube?

irish_tyrant

Thanks Bob, I'm fairly certian that there all routed properly. I was very diligent about labeling everything when I pulled it. I will double check the routing though. I hosed this area with carb cleaner a few times and no rev spike. I'm wondering if there may be a vacuum leak that I cant get to with the carb cleaner though or if the vacuum just shows low. So which of these lines would work best to throw a gauge on and how much vacuum should I see?

irish_tyrant

I cleaned the intake plenum out really well but not the EGR.

93toyrunner2

http://www.ncttora.com/FSM/1990-1995...e/throttle.pdf
Page 7, step 4. Is this where you are putting the gauge?
As far as vacuum, I do not have any info on this.