The Engine Hesitation Saga

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AYM707

AYM707

10 Year
Joined
Dec 24, 2013
Threads
68
Messages
377
Location
Toronto, ONT
For the longest time, I had a concern on the engine hesitation. Initially, I did not really notice anything; but a local mechanic in KSA raised concern and then "fixed" it. In reality, he just screwed it up and made it worse. Repeated visits did not help.

After importing the vehicle to Canada, I continued to experience the engine hesitation to the point that I had to do something. I know it had to do with the distributor, cause that's where he work on. After doing my research and alot of help from @MatthewMcD / @65swb45 / @pb4ugo and others... I resolved it must be a dwell angle issue. Using a mutli-meter, measured the dwell and realized it was 36 degrees, while specifications is 41 degrees (+/- 1 degree). Stepping out of my comfort zone, I managed to single-handedly adjusting the dwell. I also changed the distributor cap (which was cracked) & rotor. Unfortunately, now my engine was misfiring!! This was super depressing.

I needed to adjust the distributor; but this was way ...way beyond my capabilities / comfort zone. Lucky, was able to reach out to the local FJ40 community in Ontario, Canada and Chris Onyschuk volunteered to help me. He is a gem of a person!!! The distributor was set 12 degrees btdc while spec is 7 degrees. He also helped me re-adjust the engine speed / carburetor fuel ratio. Took it for a spin and no misfiring!!!

I was also experiencing start-up issues. It would take forever to cold start, and sometimes, it would not. The engine would crank but would not kick. Initially, I thought it was a battery issue but replacing the battery did not resolve the issue. AI researching, pointed toward the external ballast & ignition coil. Tested both and the external ballast was bad. I replaced it with an older ballast, I had and it started right up. Eventually, I replaced both the ballast and coil and thought all issues were behind me.

Went for a long drive, and after about 1.5 hours, it misfired a few times and as I continued to drive, starting feeling the engine hesitation. Super frustrated!!!

Back to AI research which advised an epoxy filled ignition coil is best suited for horizontal applications. Original Toyota is oil-filled and tends to create hot spots which my cause misfiring and engine hesitation. Thinking to go with the PerTronix 40111 (1.5 ohms) coil with the external ballast. I had purchased a NGK 49030 replacement coil; which is oil-filled.

I also checked the spacing of the engine valves. With the engine hot, the spacing between the valve springs was extremely tight...I could not get the feeler gauge into the gap. So I loosen / adjusted the valves. AI research also said that tight valves may also cause misfiring and/or hesitation especially when the engine is hot. Will go for another long drive to test if this improved the situation.

Sorry, this was a bit long...but I would appreciate your input on what other things I need to check. What's your experience with PerTronix 40111 (1.5 ohms) coil?
 
Check the compression dry and then wet. You might have already burnt valve(s)!
Put a bottle or two of gas dryer in the tank - warm days and cold nights will condense water out of the air right into you tank and the station too. New fuel filter - paper element will not pass fuel correctly if wet with water - set old one in the sun for a few days, it will dry out and be good again - I rotate threw 3 units. I have a oiled foam air filter.

I normally run more straight mechanical advance than that. I consider dwell as hyper critical points gap adjustment. Spark plug gap needs to be correct and have a square edge.
 
If you have an engine electrical/ ignition issue that destabilizes over time, internal corrosion in the wiring may well be the culprit, as resistance increases with heat. Running bypass wires in each of the segments in the system is a good way to test this.
 
You will notice a big improvement with property adjusted valves.

Ive experienced hesitation as well. For a long time, the biggest cause on my end was the exhaust valves would constantly tighten on my 1f engine. About every 500 miles. The previous owner would only turn it on for 5 minutes, let the oil run for a bit, then shut it off.

The valves were pretty gunked with sludge/oil after I checked by removing the intake and exhaust manifold. Cleaned it out with diesel and a tooth brush. Doing that, plus daily driving it and eveything finally broke loose.

Aside from that, another issue that is/was common for me is the jet size and type of fuel for the carb. Okay, so the orginal carb jets was most likely build for ethenol free fuel (not this corn crap fuel we see today). And the orginal jets were more "lean". My original jet size was 112.

When I fuel up with ethenol free fuel, cold starts are not an issue, I feel the engine idle smoother, and zero heiststion.

If I put regular fuel (which may contain ethenol corn crap) I experience stuttering/hesitation when I make left or right hand turns and I step on the gas again.... No hesitation in straight aways with crap gas.

So, you either keep your current carb jets and run ethenol free gas..... Or, go up a couple of sizes on the jet and it will deliver more fuel and should stop hesitation with regular corn gas.

Hope this helps :]
 
Problem 1 .... your asking AI

could be revolving around carb issue... what carb do you have? OEM? Weber? Weber clone? other?

points?

last time you did a full tune-up?
 
Thanks for the shout out. I have to agree with others on the fuel delivery side. Fuel filter and clean or rebuilt carb. If you can get it to stutter in the shop check for vacuum leaks, but it sounds like a fuel issue.
 
JohnnyC said:
Problem 1 .... your asking AI

could be revolving around carb issue... what carb do you have? OEM? Weber? Weber clone? other?

points?

last time you did a full tune-up?
Click to expand...

Agreed, I'm not a big fan of AI, dont trust it!! but have found it a good / quick way to do research.



charliemeyer007 said:
Check the compression dry and then wet. You might have already burnt valve(s)!
Put a bottle or two of gas dryer in the tank - warm days and cold nights will condense water out of the air right into you tank and the station too. New fuel filter - paper element will not pass fuel correctly if wet with water - set old one in the sun for a few days, it will dry out and be good again - I rotate threw 3 units. I have a oiled foam air filter.

I normally run more straight mechanical advance than that. I consider dwell as hyper critical points gap adjustment. Spark plug gap needs to be correct and have a square edge.
Click to expand...


So i did a dry & wet compression test. My first attempt, the results were quite disappointing :
Image (50).webp



But I thought the low results was related to my bad technique, so I re-did the dry compression test, and the results were much better....

Image (53).webp


I did not repeat the wet compression test, as the dry test was within acceptable tolerances.

I also changed my spark plugs. Previously, I was running NGK BPR5EGP; but (using AI to research I8HMUD forum comments) general consensus was that NGK BPR5ES plugs are best for 2F. Checked / adjusted the gap for .032 in.

Lastly, adjusted the carburetor. I am now running at 700/720 RPM @ 20 in Hg. so I think I am good?

I want re-check my valve spacing. Previously, on a warm engine I was setting the Intake at 0.008 in & Exhaust at 0.014 in. That's aligns with the Haynes manual but have also seen references to exhaust valves at 0.012 in (warm). Any comments?

I need to take her for a spin and see if there is any improvement.
 
I had to buy one of those compression tester kits that screw into the spark plug hole - I don't have the strength to just press on my old one and use the remote starter. It was off Amoron and only like $20.

I set the valves on the loose side of specs - better to hear them than burn them IMHO.
 
MatthewMcD said:
When you do the compression test, make sure the carb is WFO.

Have you rebuilt your fuel pump?

M
Click to expand...
What's WFO?

I have thought of replacing it, but was not sure if that was the root cause of the problem.
 
charliemeyer007 said:
WOT is wide open throttle. Helps get faster results on compression tests.
Click to expand...
that's why I re-did the dry compression. First time around, I did not have the throttle open & the adaptor hose was not properly screwed in.
 
AYM707 said:
that's why I re-did the dry compression. First time around, I did not have the throttle open & the adaptor hose was not properly screwed in.
Click to expand...

Did the results change?
 
just going back to the ignition coil. I am currently using NGK U1173 with an external ballast (1.6 ohms). I was "advised" that is incorrect, as NGK U1173 is to be used without an external ballast. I dont want to change my wiring, so thinking I'll just install a PerTronix 40111.

Any thoughts?
 
Usually, if the coil doesnt require an external ballast means it has an internal ballast. You can throw money at it or just bypass the external ballast and see if it makes a difference.
 
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