Gargoyle_Runner

So my 86 4Runner ran great. Lost the belt on the water pump driving down the highway but thought it was just a lost alternator so continued to the next exit. Watched the temp gauge and it never went up. Turns out that wasn't working proper. So the motor went way hot and crapped out. I had a local machine shop rebuild the short block with an EngineBldr master kit 20 over. Purchased a complete super stock head with 268 cam from EngineBldr also. While everything was out I cleaned all the muck out of the intake. Pretty much every part was stripped down and scrubbed in a bath of cleaner, primed and painted. Checked the impedance on everything. Cleaned the IACV and removed and blocked off the EGR etc. Reassembled and fired it up. I had to go through and improve my grounds, downside of painting everything but otherwise fired right up.

So the problem. As the motor warms up the idle starts to go rough. It also picks up a miss. The cold start goes to @1100 RPM and sits perfectly still and smooth.

I've got no codes. Timing is at 8*, I've played with that a bit going up a few degrees but no improvement. The TPS was set proper originally but went through it again. Coolant level is good. I've metered the AFM.

I have not checked the fuel pressure but it was fine before the rebuild. The injectors are a performance after market I installed last year and worked just fine before the rebuild. When I pull the vacuum line off the FPR the idle improves but doesn't totally smooth out and still has a bit of a miss. I've pulled the plug wires on each cylinder and get the same response from each cylinder. So there are no redflags as to a particular injector,plug or wire.

My thoughts are that when it starts cold and all 5 injectors are working it's a happy motor. As it warms and the CSI starts to stop working the four remaining aren't doing enough.

It drives good but when not under load I can feel the miss. Getting @20mph which is a wee bit better than before the rebuild.

Any words of advice would be greatly appreciated. I drive long spans often and fear that this is something little that could become something big several hours into my commute.

muddpigg

iTrader: (1)

Did you short terminal to set timing?

Are you positive that your not off a tooth on distro?

Remember when cold the engine is running in open loop so it doesn't require input from O2 sensor for mixture. The CSI should cut off very soon after engine turns over.

EGR is stuck open?

Gargoyle_Runner

I did jump the connector. I actually put a toggle in the cab that jumps that for me so I can check codes on the fly. I removed the EGR. I have not metered the 02 sensor but I did check it's ground resistance. That was a problem at first.

Gargoyle_Runner

I have played with the dizzy also. I was off a tooth at first install.

jennygirl

Sorry to hear about your issue. Crap idle and missing at idle seems to plague a lot of us.

Have you fully burped the coolant system? Air trapped in there throws off the ECT and totally futzes with closed loop warm idle.

I would also triple check your ground locations- specifically the one for the injectors connected to the intake manifold.

Also have you adjusted idle up where it should be once warm? I think at lower rpms the alternator doesn't put out as much juice which might lead to crappy heartbeat on an old harness with gunked connections. Sometimes raising the idle to where it should be (some say 750 some say 900) is enough to smooth it out with more voltage. Try some dielectric grease on everything heartbeat and sensor related (grounds, injectors, ignition, AFM, ECT, alternator connector).

jennygirl

Also forgot to mention.. I just recently notched my AFM 4 clicks richer and it made a world of difference. I was skeptical at first because the ECU should adjust AFR automagically from the O2 sensor, but it both smoothed out idle and gave a whopping amount of torque at WOT that I never knew I had. I think I was running a bit lean even with the minor upgrades (headers+intake).

Maybe with the rebuild bonuses you are flowing a bit more, and the engine wants a richer mixture? It might be worth a shot to try if you haven't already

Gargoyle_Runner

I have thought about the AFM adjustment. I've read the debates on that but something that somebody posted that made sense to me was that the AFM was set by the factory at a time when fuels were different. It makes sense that the adjustments should be different now. After fixing my temp gauge I realized that my Runner was running cool so I popped the thermostat out to see that it was locked open. It was just an Autozone 8 buck special so no surprise. So I stop by the dealership today and dropped 17+ on a new one. Dropped it in and drove around the block and watched the temp climb, and climb, and climb. Almost reached the red before opening up and the temp quickly dropped and then climbed, and climbed, blah, blah, blah. OEM faulty out of the box. So I will swap that tomorrow and then adjust the AFM. I took the dremel to all ground locations to make sure I'm on bare metal so my grounds should be fine. I'll fill you in tomorrow if there is any change after I adjust the AFM.

Thanks for the help

Gargoyle_Runner

Adjusted the AFM while the motor was running and each notch caused the it to idle better and better. I've still got an air bubble giving me grief though. It runs great and then the temp starts rising gets close to the top and then just drops back to just under half. I was checking things out, radiator was full but when I pulled the ECU temp sensor out there was no fluid flowing out of the hole. I didn't expect much with the rad cap on, but I expected something. I've done the whole park on a hill run it with the cap kind of loose thing. But still have a bubble I can't push out.

jennygirl

Great to hear that your AFM adjustment made a difference. How many notches did you move it? I think I have mine set at 3 towards rich, might need to up it even a few more.

Did you replace that faulty OEM thermo yet? And is it the 2 stage version or single stage? There was a service bulletin about moving from the single to the double.

This is the one I run in mine, I got it from LCE. Works well so far, and the temp gauge never goes past horizontal- actually sits a bit under at the highest.

OEM 2 stage 190* thermostat

Gargoyle_Runner

I ended up going 4 notches. The idle improved with each notch.

I purchased the thermostat from the dealership but it is a single stage. I wasn't even offered a two stage. For my own curiosity I tested it. I dropped it in a pot of water with a thermometer and it opened slowly at 190+ and fully opened by 200. I'm curious about the two stage option.

What is your MPG with your AFM setting?

jennygirl

I am trying to find the service bulletin I have in mind about the thermostat, but I'm pretty sure they should be giving you the two stager for this very reason.

I just got back from a round trip from LA to San Diego, so kind of great timing for you to ask about mpg

27.5 on the way there (avg speed 47)
22.2 on the way back (avg speed 59)

The trip on the way there is one for my record books


On the way there I was focusing on keeping it around 50-55, and there was some traffic dispersed which I always manage to keep a steady 30mpg with the right timing. I wasn't doing any crazy drafting or anything either, just simply keeping my foot steady on the gas. Due to the mpguino, I probably pay way more attention to mpg... So it's kind of hard to judge.

On the way back, though, I was being much more liberal with my throttle. I decided to see what I would get holding it at 65. There were some moments of slowing to 45-50, and some moments going over 70. Pretty average driving with not much attention paid to hypermiling.

jennygirl

Btw, I have LCE headers, intake/battery swap, new denso plugs n wires, and 170+ compression across all cylinders... and 492k on the odometer But I'm pretty sure the previous owner had her rebuilt not long ago. Needless to say I am so flipping happy to see those mpg numbers! When I got the car the most I could hit was 18-20.

Gargoyle_Runner

Still chasing my idle issues. I put a meter on the O2 sensor and it was out of range. Not enough to blink a code for me but enough to swap it. I dropped a Denso sensor in and not much change in the idle. I can notice a change in the drive. I have more low end, but still a shaky idle. The idle is a little high currently 'cause it runs smoother, @1000. Of I dropped it down to 800 it shakes the shifter back and forth quite a bit. It runs smooth when cold while in open loop which still points to a sensor in my head. I've checked everything else I can think of. Scratching my head as I type.

jennygirl

Well I'm going to join you on the head scratch party. I have exactly the same thing, it just seems to be so intermittent. Literally the exact same symptom with the shifter!

I think I am going to try a different ECU and see if that makes any difference at all. My roommate also has an 87 and his doesn't do the idle shudder thing as far as I know.

Oh, gremlins gremlins gremlins!

Gargoyle_Runner

I got mine wet. Or did I feed it after midnight? I can't remember....

Gargoyle_Runner

I've been reading about people who have had injector issues after warm up but I'm not sure how to check that other than swapping the injectors out. I've pulled cords to see if one cylinder is the problem but if the problem is small enough than a dead cylinder would mask it. Let me explain that better. When I pull the plug wires I get the same reaction from each cylinder. But if one injector is just a bit off it doesn't stand out against a dead cylinder, so it can be masked. The injectors are only a year plus old. I haven't tested the fuel pressure yet and I don't know if that's something that can or would change as the motor heats up. I've pulled the vacuum hose from the regulator and the idle gets better but doesn't go proper.

Gargoyle_Runner

The search for answers continues... So I started thinking about ignition. Everything seemed to be working but plugs are cheap and easy so I'll try that. I was running NGK V power and they were only a year+ old. But for less than 10 bucks I changed them out and that did make a difference. It still doesn't idle as butter smooth as when it first starts but it's certainly more smooth than it was. One thing I was noticing on my drive to the parts store. As I would go down hill coasting in gear I could still feel the miss or hiccup. When the motor is turned by the vehicle and not because it's being fed fuel and spark, why would it miss? I started to wonder if it was in the exhaust. Perhaps a collapsing cat even though I feel good pressure out of the pipe. But swapping the plugs seemed to fix that issue also. But I can't wrap my head around why.

jennygirl

Something I've been messing with recently is the idle mixture screw in the AFM. Basically it is a controlled vacuum leak. I've read a lot of controversy over it, and it didn't make all that much of a difference, but perhaps it would for you.

Do you know if you're running rich or lean? I think running a bit lean around idle will easily cause a hiccup/miss.

Also, check spark gap. It's possible that you might need to adjust with the different build. Actually I noticed a massive difference with my idle hiccup when I adjusted gap to .032 and set timing to 8*. I seem to have found a good combination between spark gap, idle mix screw and AFM spring tension, and timing that has helped to diminish my idle hiccup to almost nothing. I also suspect the previous owner did some stuff during the rebuild that must've happened right before I bought the truck.

AFM spring
- 2 clicks richer
AFM mixture screw
- 1.5 turns richer
Plugs
- gapped to .032
Timing
- 8* base timing

Running pretty well now. I dunno maybe this will help you as well. I've got practically the same kind of idle thing it seems!

EDIT: forgot to add, out of the box, my denso double platinums were gapped to .042. I think the NGK's are similar or even closer to .045 off the top of my head. I'm pretty sure the FSM calls for .032. One more thing, I'm pretty sure the NGK's say don't gap them... They are brittle?

Gargoyle_Runner

Woo Hoo!!!! All good.

So I'm the type that thinks when things go suddenly bad it's because one thing went bad. Sometimes a basket of ˟˟˟˟ goes wrong. I read a thread about someone with a similar problem that ended up being the fuel pump. I clamped off the fuel return hose and presto the idle evened out. So I dropped in a new pump and the idle sounded a lot better and the miss was gone. Something still wasn't perfect. I checked the codes and it was flashing 7, the TPS. That is the first time that code popped up and I've checked alot recently in my quest. I put a meter on it and the numbers were off. So I dropped in a new one and adjusted it according to 4crawlers instructions. Purrs like a kitten. I've still got +4 notches on my AFM all though I'm thinking of toying with that adjustment screw. I'm curious if I back off a notch or so and bump that screw what it will sound like and how my mpg will be effected. I'm running @20 mpg now which is what it was before the rebuild. Now I'm 20 over with a 268 cam on a super stock head. This is the first time it's been running smooth since the rebuild so I don't have a base line to know if I'm getting what I should mileage wise.