Low idle after rebuild (1 Viewer)

[Honeybadger80]

I just got done with my rebuild of a 1fz on my 94 and on start up its sounds and runs great. After about 15 seconds it starts to idle really low and stalls out, and in the process the check engine light comes on before it dies. It fires right back up with no CEL and does the same thing . I can keep the rpms up manually and keep it running but i want to check timing on it, my idle is either to high or to low soits making it hard . Any thoughts? I jumped the terminals in the diagnostic box and heard the idle come down the first time i tried to time it after that i dont notice any difference when i jump the te1 and e1. Maybe its just cause the engine speed isnt right. I tried my best to keep the cables on the throttle body in the same position but its been a month or two three since i took them off the engine. Is there a good way to tell if they are set up right? Could it be this simple? Any advice is well appreciated here.

 

[fjbj40]

Check TPS as per FSM.

 

[zapatius]

I just got done with my rebuild of a 1fz on my 94 and on start up its sounds and runs great. After about 15 seconds it starts to idle really low and stalls out, and in the process the check engine light comes on before it dies. It fires right back up with no CEL and does the same thing . I can keep the rpms up manually and keep it running but i want to check timing on it, my idle is either to high or to low soits making it hard . Any thoughts? I jumped the terminals in the diagnostic box and heard the idle come down the first time i tried to time it after that i dont notice any difference when i jump the te1 and e1. Maybe its just cause the engine speed isnt right. I tried my best to keep the cables on the throttle body in the same position but its been a month or two three since i took them off the engine. Is there a good way to tell if they are set up right? Could it be this simple? Any advice is well appreciated here.

Is your distributor on the correct tooth? Is your throttle cable at the correct tightness?

 

[Honeybadger80]

Is your distributor on the correct tooth? Is your throttle cable at the correct tightness?

Ill check both both of those once i got some coffee in me and report back. Also ill dig through my FSM and see if i can find anything on the TPS but i think i only had printed about 400 pages of engine rebuild goodies ill see if thats in there with what i got

 

[zapatius]

Ill check both both of those once i got some coffee in me and report back. Also ill dig through my FSM and see if i can find anything on the TPS but i think i only had printed about 400 pages of engine rebuild goodies ill see if thats in there with what i got

If you're one tooth off, but have the distributor cranked all the way over, it will run roughly and may die...but it will run.

 

[Honeybadger80]

Havent gone to check this mornimg but soon ill be out there i think last night the distributor was pushed pretty far down to get close to 3° . If its off a tooth is it just a 50 50 chance of roating it the right way back a tooth ? Is there a good way to see if i take the cap off that im colse or getting further off

 

[alia176]

by rebuild, do you mean a head gasket job? If so, i agree with others, check your dizzy timing, TPS and also IAC. IAC is in charge of your idle.

dizzy check - #1 piston on top of stroke (confirm with a long rod, screwdriver through the spark plug hole), timing mark on zero degree BTDC AND, dizzy rotor pointing to #1 spark plug.

Let us know what you find out! It's something silly, usually!

 

[zapatius]

Havent gone to check this mornimg but soon ill be out there i think last night the distributor was pushed pretty far down to get close to 3° . If its off a tooth is it just a 50 50 chance of roating it the right way back a tooth ? Is there a good way to see if i take the cap off that im colse or getting further off

You have to set crank at TDC, take the cap completely off, pull the distributor completely out then re-engage the gears with the correct alignment.

Generally, in my experience, if you have it one tooth off, you will have to crank it all the way to the stop to get it to barely run.

 

[Honeybadger80]

Okay got it running and idleing smooth. Im assuming i was off a tooth. Anyways at idle it runs and sounds great but as i bring up the rpm it seems to loose power around 2500 rpm or so and when i let off it just hangs out there in that rpm range where it happend untill i shut it down even if i manually push the throttle all the way back down. I dont really know how to explain the issue that well and a video sound isnt really doing it justice. Ive never delt with valve float but is that something i could be dealing with here. It sounds like in midrange that it all flatens out and make no power. My rebuild was for a HG leak when i bought the truck so i never even got to drive it around or anything before i tore into it witch could also be an issue i guess. But anyways i followed the book very close if it went back on the engine i found it in the book and installed accordingly. I did a head surface and cleaning bored and honed the block all by a local shop full engine gasket set new pistons rings and all the goodies i used almost all oem parts except pistons and rings. Sorry for the long post and poor discription of whats happening ill be at it again today so if anything sticks out let me know i could use some help.

 

[Honeybadger80]

Also if anyone is in the wenatchee WA area that wants to take a look i got cash and cold drinks for your services !

 

[alia176]

Bummer, you're still having issues.

Were you able to re-install the two cam shafts exactly as FSM described, including putting a 10mm bolt on one socket so that the two halves stay in synch with one another?

Valve float sounds like something a hi performance engine experiences at stupid high rpm, which you aren't even close to, I don't think!

Please perform the tasks I outlined in post #7 and report back.

 

[cvenom96]

Definitely check to see that timing is correct as stated. When I did my head gasket, I was close but it still was way too much timing. It would crank but after about 15 seconds it would start to miss and eventually die. Once the timing was set it was nice and smooth. As far as it hanging at 2500 or so, are you sure the throttle is closing? Like you're closing it at the throttle body? Mine used to do that until I replaced the throttle cable. Typically it was only after driving it for a while and it was nasty hot out. With it running smooth but then getting stuck at an RPM it's got to be a sensor or something.

 

[Honeybadger80]

Yeah its a defeating feeling i have but obviously not giving up it doesnt sound anything catastrophic so i know it can be solved. What are people timing to on these some people i have read are saying 7° but fsm says 3° btdc and thats what i did. Timing light was set to 0°advanced like its manual says then clamped on number 1 wire and jumped te1 and e1 engine was warmish when i did it and my mark is dead on at 3°. As for the cams i did do what it said and checked my clearances all were well within spec. my throttle cable cover is definitely worn out and my pedal feels stiff to me but again my its first 80 and ive never drove this one specifically. I was throttling it by hand in the engine bay. The cable doesnt hang up or anything just not the smoothest . Ill check my tps and iac today but i got to get my new castor bushings in and get the radius arms back on then lower this pig a bit to work on.

 

[Honeybadger80]

Also with the original issue my intake hose to the MAF was cracked found that out real quick when it split completely in half when i took it off . So its glued and rtv until i get a new one

 

[alia176]

Just a tip, regarding floor jack under the front axle If you remove the wheels, place the floor jack under front the axle housing, to the right of the front diff, the whole thing balances itself nicely. Then, lower the front of the 80 until the brake rotors are one inch (or less) away from the floor. Place a wood under each rotor just to play it safe. This really helps with working on the engine bay w/o having to reach all that hard.

 

[fjbj40]

Ck accelerator cable and tps rigging

 

[Honeybadger80]

I know the answer to this one is to go by the fsm but any tips advice experiences for tps set up i pushed on the linkage at the sensor that connects it and it stalled. I never messed with its position durring the removal and install and it along with everything has factory paint marks still lined up. im not saying its not bad or faulty though .

 

[ppc]

When you set the timing and jumped te1 and e1, did you also verify the CEL was flashing at a regular pace?

As stated previously as define valve float occurs at very high RPM when the valve springs are not strong and fast enough to close the valves. Not something that happens with the LC

Could you describe further the conditions when you use the word hang:
"but as i bring up the rpm it seems to loose power around 2500 rpm or so and when i let off it just hangs out there in that rpm range where it happend untill i shut it down even if i manually push the throttle all the way back down."

The IAC has nothing to do with your problem as that only controls idle speed. However the TPS is very applicable to the problem.

After that then it might be time to pull the valve cover to check the proper positioning of the cams. Rotate engine to TDC on the compression stroke and then make sure number 1 cylinder has both intake and exhaust valves completely closed. Having the timing chain one tooth off might be your issue.

 

[Honeybadger80]

Good to know ive never expericed valve float so i didnt know.
I did not verify with the CEL normally i just hear a change in the sound and assume im good to go ill double check it.
So describing my issue right now is harder than i thought. Ive done plenty of motor work and am a confident backyard mechanic but this i just dont know what to say. So when im at idle all is good sounds like it will run indefinitely. I can give her some revs by my hand on the throttle linkage, all is good but if i slowly bring up the rpms to say around 2500 (im not quite sure im going off sound in the engine bay ) it will all of the sudden feel like power is gone something doesnt sound right not a knocking or ticking but more like everything is getting a buzz. I really dont know what to call it so i know this isnt helping my case. Thats why i say valves floating cause it literally sounds like nothing ive experienced So onto the hanging up part, when it does the buzz thing i let off the throttle and it snaps back down like it should but the rpms stay where they are. In a panic i just shuter down. Then the next start up its just fine at idle but does the same thing as i rev it up.
Its got me worried but again it doesnt sound damaging just not right . Ive got some help coming next week but id like to get this thing going.

Long boring post thanks for reading .