More ISCV questions (sorry)

[cuh8er]

A friend of a friend of mine has insisted that the engine wont idle correctly without an exhaust. The headers are on and the oxy sensors are plugged in, will it make any difference?

Setting up the throttle sensor now, though it's a little confusing.
It says:

Gradually turn the throttle position sensor clockwise
until an ohmmeter resistance is gone, then secure the​

sensor with two screws.

This is with 0.4mm feeler gauge inserted. Then the table below says you need continuity at 0.4mm. Itis contradicting itself there.

 

[cuh8er]

Ok, re-set the TPS as CJ said, and the idle is MUCH better now.
Basically at approx 0.6mm, I lose continuity across IDL and E2.

It no longer 'hunts' for a good idle. It is however a low idle (sounds to be around 400rpm).

If I pull spark plug lead 3 or 5 (only tried these) there is no change in engine note or engine behaviour (revs).

There is spark at the plugs.

I have swapped igniters.

I have swapped coils.

Injectors are fresh from a professional clean.

There is 220psi compression in the cylinders.

No codes are being given.

I have belled out the wires to and from the igniters. The only difference is the trigger wire going from igniter 1 to the coil has approx 0.1ohms across it while igniter 2 has 0.75ohms to the coil. A substantial difference in my opinion, but there is STILL spark at the spark plugs. Maybe not strong enough of a spark....?

What could be the issue now....? HELP!!!!

Thanks again.

 

[cjsupra90]

Back to this issue. Are you sure that you dont have the #3 and #5 wires flip flopped on the dizzy cap?

They are fired in sequence on the Right bank dizzy cap so the could easily be flip flopped.

Looking at the dizzy cap plug wire towers on the Right bank (driverside for you being in AUST.) from left to right, the towers should be 2,8,C,3,5

Here's an illustration of the layout. I would dubble check all of them just to make sure that none are flip flopped.

 

[cjsupra90]

The resistance problem shouldn't be an issue. Total circuit resistance is still low enough even with with .75ohms of the wire that you should still be producing more then enough spark.......

With the specs that you provided of .75ohms and using the highest coil primary resistance of .65ohms this would give a total circuit resistance of 1.4ohms and this would equal about 9.6 amps of currect flow ability and pretty much most engines at idle only need about 3 or 4 amps of current flow at the most to produce a good strong spark at idle and usually only about 6 to 7 amps under heavy power load to still produce a good spark. You having 9+ amps of current flow ability should not be giving you any problems.... If you are concerned with the leed resistance of the one primary circuit wire, you could just run a new wire that way you know that its not a possible issue.

 

[cuh8er]

Just rechecked your diagram with the plug leads and as I thought, they are all correct.

I just went out then and tried something else.
When the engine runs at idle, if I remove spark plug lead 5 it makes no change to engine note. If I replace it and remove number 3, it's the same. No change.

I just unplugged the coil primary plug and it stalled straight away and would not start without that coil.

If I short the plug lead from 5 or 3 to the plenum, there is a spark, maybe not enough?

Also, when it's idling, if I crack the throttle and attempt to lift the revs a little, the missing/running on less cylinders is much more violent. Once the revs come up more and more, it smooths out.... Not sure if it's related at all though.

Thoughts on this?
I'm heading out now to replace that wire.

Thanks

 

[cjsupra90]

Check the resistance of the plug (high tension) wires namely them #3 and #5. Typically, OEM type wire will have about a 1000ohm per foot or per 300mm

If its isolated to those two cylinders, then it can only be a few things causing the issue. Either the dizzy cap, the wires, the plugs or those two cylinders themselves like a blown HG between those two or something of that nature.

 

[cuh8er]

Lead resistances as follows.

Right coil.
2 - 5.1k
3 - 15.11k
5 - 16.16k
8 - Open Circuit
Coil -6.8k

Left coil.
1 - 23.75k
4 - 43.0k
7 - 10.64k
6 - 23.0k
Coil - 5.35k

 

[cjsupra90]

Wait, #8 had an open circuit???? Now that doesn't make much sense.....

The other thing is they all seem a tad high, but not enought to really be giving you a problem with the exception of possibly the #4 which didn't seem to be an issue from what all you've said in the past.... The #8 is the big concern here... You might want to look into a new set of wires.. With out going back and check, I dont recall if you said that you installed new dizzy caps and rotors or plugs. You might just want to go ahead if you haven't done so and replace cap, rotor, plugs and wires. It could just simply be that a turn up is in order...

 

[cuh8er]

Thats it.
I have a new set of leads on their way, will fit them up and report back, but I'm sure this has to fix things.

Some of the high resistance leads would change their resistance when I moved the wire around so they're definetly not working as they should. I measured them using a high end Fluke meter so the values are accurate.

The only thing that worries me now (and i'm hoping will be fixed with the new leads) is the way the engine stumbles when I just crack the throttle. I can kind of see how the 2 would relate (stuffed leads and rough just off idle). Just crossing fingers at this stage.

Regards

 

[cjsupra90]

Yeah, Ignition problems can cause some strange things to happen..... With the open circuit on the one wire and resistance values changing when wires are moved around is a definit problem...

There is an old saything in the american classic car and hot rod community that is so true in every sense.. The saying is 95% of all carb and fuel tuning problems can be found in the ignitions system and distibutor!

I cant tell you how many times Ive delt with cars that people though it was fuel related or a major electrical issue and it was something simple like plugs, wires, dizzy cap and or rotor button

 

[cuh8er]

Update time.
New leads fitted up.
It still has trouble firing though.
Idle is low as a result. It is however, a little better with the new leads.
every few seconds it fires on the dead cylinders and starts to sound like it's running good, but then reverts to the 1UZ of old.

How expensive are the dizzys to replace and what part numbers should I order?
How hard are they to replace....? Are they a single part or made up of a few different parts?

This should be the next parts to replace....?
Thanks again.

 

[cjsupra90]

They are not your usually dizzy's with electronics and what not like older cars.. All you have to worry about is the caps and rotors.. They are very simple to change, just remove the plastic covers on the engine and there are 3 screws that hold each cap on and then 2 screws that hold the rotor on under the cap (6mm IIRC).... All the parts only go one one way so you dont have to worry about messing anything up.

As for price, I dont know as I have never had to buy them (I've been running COP since day one)... They shouldn't be expensive though. I would venture to guess at the most $20usd each for the caps and $10usd each for the rotors. Like I said, I wouldn't expect them to be any more then that and probably cheaper... You should be able to get them from a local parts house there... Also, change the sparkplugs too.. Chances are, if its been missfiring, it has or is starting to foul out the plugs..

 

[cuh8er]

Ok another update.
Changed rotors and caps, and it's still the same.
Seems to be getting a little better with time, but still sounds like a 5 cylinder 1UZ.

I am thinking about replacing the plugs tomorrow, but am not confident as the plugs are pretty new. Can they foul up that quick? The plugs are black all over, and the ceramic parts are black too.

I did a test where I had cylinder 1 as a good cylinder, and 3 was a 'dead' cylinder (pull the lead from cylinder 1 and the car would really struggle, where as with 3 there is no real change). I swapped the plug from 1 with the plug from 3 and the problem stayed with the cylinder. That is, pull the lead from cylinder 1 and she would nearly stall.

Only thing left on the ignition side is the coils, but I tested their cold resistence and they're well within spec.

Compression on the cylinders is around 220psi, I doubt a BHG very much.

So, where to now? I'm clutching at straws now.... Is there no way the ECU could be causing this?

 

[cuh8er]

Something I just thought of, what plug gap is recommended for a stock engine?
Pretty sure mine are gapped to 1.1mm.

 

[Bushwhacker]

Are your main O2 sensors working? If they're not this would cause overfueling/misfire/sooty deposits.

 

[cjsupra90]

Something I just thought of, what plug gap is recommended for a stock engine?
Pretty sure mine are gapped to 1.1mm.

That is the correct gap, plus the OEM ignition system has proven strong enough even if that gap were to big, it should still fire the plugs with no problem......

Are your main O2 sensors working? If they're not this would cause overfueling/misfire/sooty deposits.

This is not an issue with his problem. For starters, we had gone over diagnostic codes that he had. There were no diagnostic codes for any O2 problems in his system. The TCCS is VERY good at seeing O2 faults.. The second part of why this isn't a problem is that he has the problem right from start up. Closed Loop feed back control (i.e. needing the O2's) does not happen till the engine is closer to operating temp. I dont remember exactly what temp the system looks for and changes over to closed loop (and it varies too from system to system) but I want to say that its somewhere around 150*F (65*C). Below that the system doesn't care what the O2's are saying.

 

[cuh8er]

Cheers fellas.
Had another crack this morning.
I pulled all the plugs out and gave them a good soak and a clean in petrol and WD40. Gave them a good scrub and put them back in.
Fired it up and the engine ran MINT, for around 10 seconds, then reverted to the 1UZ of old.

Pulled the plugs from the dead cylinders and they had fuel (from what we could tell) on them.
What would cause the plugs to stop working so quickly?

Also swapped injectors over, and the 'dead cylinder' problem remained on the same cylinders.

Also got the old man over with his scope and checked the pulses to the injectors and coils, everything is in check there too. Can post pictures of the print outs if anyone is interested.

Don't really want to replace the plugs if they're going to clog up again is all. Where to now....?

 

[Zuffen]

Try replacing the plugs with a set of copper plugs.

They don't cost much and are more "foul resistant" than Iridiums.

I know you must be just about sick of this but have you tried swapping rotors between distributors. If this doesn't change the problem to the other side of the engine try swapping the caps and rechecking.

Sad to say it's aprocess of elimination but at the same time you don't want to keep spending money on replacing perfectly good parts.

I swapped plugs over 30 times in 14 days trying to get mine to run before we discovered a sheered cam drive pin which put the cams out of phase on one bank but left the distributor at the correct timing mark.

 

[cuh8er]

Thanks Rod, 'sick' is an understatement, it wouldn't be so bad but the we're meant to be heading away on a holiday this Friday so i'm under the pump big time. These issues have put us back 3 weeks now.

Rotors and caps are all new, genuine Toyota items.
New leads too.
Plugs were new, but look a little crappy due to the issues i've been having.

Would faulty coils cause fouling? I tested the cold resistance and it's all well in spec, but I read a post by gloverman saying that the coil may still be faulty, only producing 15 or so kV. With the plug out, I can see a spark, but within the high compression environment of the cylinder, maybe a different story....

Thanks

 

[cuh8er]

Ok still on this, can someone tell me why the base timing at idle is up around 20 deg?
Seems very high to me. Is there ANY adjustment for this? Can a stuffed ECU cause this?