10 psi bog sesh

[Skym]

I was talking about the loss of boost. Can lose around 1psi of boost from running engine lean + ECU pulling ignition timing due to knock.

The missing part is most likely the MAF + boost cut or airleak around the MAF somewhere or weak coilpack.

When the hotwire burns out it goes black on the cylinder part of the hotwire and that black spreads onto the wire next to the cylinder part. If cylinder part looks dark brownish (which most are at this age, high km) then it should be ok. You'll need a magnifying glass to check the hotwire out and good light (sun light).

TPS affect's transistion fuel enrichment. TPS + ECU settings prevents engine going suddenly lean when throttlebody suddenly opens (suddenly lean = hesitation, then engine accelerates). From what I understand, it's there because the MAF is to slow to react to sudden changes in airflow.

[chitrees]

UDATE:

Ok boys, MAF seems to be fine.

1.63 V COLD startup Idle
1.18-1.20 V WARM Idle

NO discrepancies in neutral rev range. Goes up to around 3.33-3.50 V. High rev, not ALL the way. Wasn't in the car when looking at voltmeter.

Car dies almost instantly when MAF is unplugged. Shouldn't the car still be running without the MAF?

Can an exhaust manifold leak cause these problems?? At this point, the only thing that I can see for sure is that the manifold is not 100%.
I know you guys said that the ECU is next but I really am running away from that diagnosis. I really, reaaallly am trying to avoid getting a tune and that doing f all. Gut feeling says it's something simple. I've watched waaay too many hours of House for this to be a mundane "brain" case.

ALSO….
I hear "hiccups" in the exhaust during idle. Basically a nuance in idle sound. Is this the car missing at idle or are these fumes igniting in the exhaust due to it running rich? Is it lean detonation?

UhhhhhggIIII don't get it. JZ where are you….

[ToroGTS]

You could have set timing wrong when re installing the CAS but that is a subsequent issue to the original. You have to use a timing light and position the CAS appropriately to know base timing is set properly.

Man if you are losing any visible spark to the head from a coil pack, then I would strongly suspect this is your issue... The high cylinder pressure of peak boost is blowing out your weak ass semi spark with what remainder of energy is reaching your plug electrodes.

[ToroGTS]

Car will not run at all without MAF, no air signal to base fueling and timing off of so ECU just bails out to be safe. Man, that 'hiccup' is a misfire at idle, again likely due to weak spark. The gas from one or more cylinders that is not being sparked off is exploding in your exhaust stream or if its just quiet, its the total non spark of that fuel mix. Having a exh manifold leak wont be great for noise either. Have you tried just tightening the manifold studs? be careful not to force it as these brake frequently.

[chitrees]

My sparking is on point ok….but na. Toro, do you have a spare set I could test? I bought packs awhile ago but they were factory packs(all 0.9 ohms), and I only got 4 'cause the seller is a dingleberry.

So when I do the pack to head test, there should be ABSOLUTELY ZERO visible spark/arcing? Where does the spark go on a good pack if not on the plug? Does the pack just "hold" that energy?

So an e.manifold leak will be really loud? Like a, "It's definitely an exhaust leak" loud? I see on the 6th cylinder the bolt/stud isn't there and there is a crack.

I feel like I've read somewhere that the ECU sets a factory setting if MAF is pulled out….am I trip pin' or what?

[chitrees]

Ok well packs fit with idle sound and main symptom, so that's good. Can my "weak ass spark" be the cause of my COLD startup issue as well? Skym verified what I thought the purpose of the TPS was. IF that is its sole function, then this would indicate an issue with my fuel enrichment sensors at startup which is an unrelated and separate problem to my main right? Unless of course my injectors have been giving me the shaft this whole time and just been chincing me out of fuel.

BUUUT if the TPS has any role in "ignition control" (Toro??), then all the symptoms point to packs and it's a clean up from there.
P.S. Why 0.49 V idle contact? What is this magic number?

[ToroGTS]

As far as the TPS, there is a 'idle contact pin' physically at the bottom of the sensor range, I believe its at or near 0.48 V on a new stock sensor. When this pin is physically contacted by a closed throttle condition then the ecu makes adjustments to optimize idle, advance timing and cut fuel to ideally around 14.7 mole o2 to 1 mole fuel.

The TPS has a role in ignition timing selection but not in actually spark delivery. Thats kind of what I was getting at with the little write up. Your sensors help select exact timing of spark and quantity of fueling by deducing air mass and engine load. The ecu interprets sensor data and delivers a 5 volt signal (through ignitor chip) to the ignition coil which causes the coil to retain energy on the primary coil from the 12v constant power wire (thick white wire on your oem 3 pin ignition harness). When the ecu ceases the 5 v signal the coil discharges all retained power directly into the spark plug, where the ONLY path of electric flow should be across the gap from plug electrode to plug body that is grounded to the head by the plug threads.

It's important to note that electricity will always take the path of least resistance in a circuit. In your case that path if from the primary coil of your oem coils out the side of your breached coil casing to the head. Only in the scenario where the amount of electricity flowing to the head out the breached case is so great that the resistance of the section of air between plug electrode and thread body is less than resistance between primary coil and head at coil casing, will you induce a spark inside the cylinder.

In short, you need to replace your coils. Personally I don't run any oem coils on any RB series motor. I don't believe the oem coils are suited for any application beyond stock turbo on max boost even new from the factory. They have been a source of problems every time I've tried to use them and I swap to GM Ls series coils in all occasions.

[Skym]

Stock ECU can run without MAF (uses a default voltage value on ECU, engages fuel cut around 2500-3000rpm). You unplug MAF, then start engine. Don't unplug MAF while engine is running. Only stock ECU has this feature.

Hiccups at idle are due to engine running lean and that is caused by the o2 sensor making ECU make engine run lean. If unplug o2 sensor the ECU will use the fuel map only and ignore o2 sensor (uses a default voltage value for o2 sensor on ECU) and idle very smooth. When the o2sensor is not used / unplugged it's known as open loop. When o2 sensor is used it's known as closed loop. ECU will go into open loop just after cold startup and at full throttle.

But if engine is running lean for some reason, it's not a good idea to unplug the o2 sensor.

TPS is for transistion fuel enrichment (stops engine hesitating when suddenly open throttle). TPS is a electronic version of an accelerator pump as used on carb engines. Idle contact tells ECU to kick rpm up to prevent engine from stalling.

If engine is not reaching the correct boost level it most likely will be ECU tune related (or a restriction on engine). Retune also fixes the cold startup on ECU. You can check this by cold starting engine, then turn engine off. Turn engine on and if engine starts normally with not much effort and not wanting to stall, then ECU tune related.

But there could be mechanical problems like coilpack, intake airleak near MAF, coilpack, ignition module (runs on 5 cylinders), injector harness (or injectors), coilpack harness to name a few area's that cause engine to missfire. They need to be checked / fixed first.

With stock exhaust manifold it warps at both ends, front and rear of engine due to exhaust swinging left to right, right to left + heat. That's why the exhaust manifold needs to be planed flat before fitting a new gasket. Can plane the exhaust manifold so amount of times before it has to be binned.

[chitrees]

Hmm…I understand Toro's theory on the idle hiccups, but why would a lean condition cause these sounds? Why is the 02 sensor causing a lean condition? Are you saying the sensor is bad? How can i check if bad/good?

If car starts after the shutoff, but with effort, does this suggest a different cause rather than the ECU tune? If so, could leaking coil packs be a cause for the startup issue? Coil packs has yet to fit with startup.

WHY DOES STARTUP ONLY OCCUR WITH PEDAL DEPRESSION? Are packs related in anyway with this? Is the pedal operation influencing increased fuel/air amount? The manual directs you to the AAC valve in diagnosing pedal depression startup.

So Skym…what is your diagnosis if to choose one? You seem to be adamant on it being a tuning issue. Out of all the mechanical problems you've listed, which has the most potential to stop my car the way it does? I feel like little things like a small leak near the MAF wouldn't stop my car straight but rather just misfiring.

[Skym]

Because if the engine is modified it runs leaner at idle. When combined with the o2 sensor making the ECU run engine leaner than it should, the result is a lean missfire. If watch voltage from o2 sensor you'll see the missfire occurs when voltage heads towards 0 (lean). It doesn't matter if the o2 sensor is new or not, the engine will still missfire (what I learnt from trial, error). A ECU tune usually solves this problem (adjust fuel map, etc to suit mods, etc).

Then most likely the hard starting when cold could be caused by CAS failing (failed CAS bearings x 2 drag, which pulls ignition timing by a few degrees and that makes the engine harder to start). That's is if coilpacks are ok, in which you said they are when tested on the bench.

I was saying if one or more coilpacks have failed or are on the way out it can cause missfiring and also hard starting. You are meant to replace coilpacks, sparkplugs at 100,000km as part of routine maintenance. Alot earlier if have thrashed the car.

Because when press the accelerator pedal you are opening the throttlebody butterfly which allows more air into engine. The start up table that's used by ECU when starting engine for the first time is very rich and way too rich when mods like exhaust are added to engine. If crank the engine for longer to get the pistons pumping and engine sucking more air in, the engine will start better, as there is more of an equal amount of air vs fuel injected by injectors.

When start engine again after first time it uses another table on ECU that's a little bit leaner, hence why engine should start easier / better. If engine doesn't start easier, start looking at CAS timing via a timing light (white sticker is on the underside of the hood, passenger side which mentions the timing info and 15 BTDC is manual trans / engine ECU setting for CAS, 20 BTDC is automatic trans / engine ECU setting for CAS), look for intake airleaks, check for sticky / dirty IACV, sticky / dirty AACV (also leaking paper gasket), faulty coilpacks.

IACV and AACV work together to provide air to intake manifold when the throttlebody butterfly is closed while engine is cold and engine is running richer at idle. The IACV provides extra air on top of what the AACV provides and slowly closes as the engine warms up (ECU runs engine leaner to match and does this via looking at coolant temp). Once engine is warm and the IACV is fully closed, the AACV takes over the supply of air to intake manifold when throttlebody butterfly is closed.

It could be many things, but without checking ECU for sensor failures, checking other parts of engine it's hard to tell. All we can do is tell you the common area's to look at and you have to eliminate those area's as a cause. It's not waste of time, as you are making sure everything is in working condition. I had to do this with my car, but it ran better and learnt alot in the process.

Most common cause of hard starting I have found is faulty CAS, faulty coilpacks, intake airleaks (before and after turbo), ECU tune.

[chitrees]

Nice info, thank you again.

So with the CAS, which bearings am I looking for to determine if the CAS is good or not?

Ok so with coil packs (which I think may be the culprit now), all I know for sure is that they are at spec. resistance. The only way my packs are bad are if they are leaking……STILL.

DEFINING TEST:

In terms of leakage, if I observe ANY (small/large spark near/far distance to head) spark from the pack (head/side) to the head when doing idle coil pack test, does this mean it's automatically shot? What would a good coil pack do? Would it not arc at all no matter how far/close to the head it is?

[Skym]

You're welcome.

Usually hard starting when cold, hot is the symptoms of a faulty CAS (most likely a few degrees of ignition timing will be lost and best checked on a dyno with a timing light or ECU tuning software). And CAS error code on ECU. But if engine hiccups it can trigger the CAS error code on ECU as CAS goes out of sync (affect's the signal from CAS which the ECU picks up on and the signal can be visually seen via an oscillioscope which some auto electricians have).

Tested the coilpacks on a coilpack test machine at an auto electrician. There were 2x coilpacks that had lower output than the rest, I think one other was slightly off, all three coilpacks eventually failed. The coilpack test machine has 2x gauges, one showing input voltage and the other output voltage. Can visually see the output from coilpacks.

Usually there is grey tracking marks on both sides of the coilpack, just under mounting bracket and on the seal between the two parts of the coilpack. All coilpacks that failed on my cars engine have those grey tracking marks under the mounting bracket. Other is the sparkplug tip becomes darker / fouled on the cylinder where the coilpack has failed / leaks. They usually fail / miss intermittently and noticed it gets worse on cold days / nights or when it rains.

You can dip the coilpacks in resin? to reseal the cracks and is a temporary fix. There are tutorials on how to do this on the internet.

[chitrees]

Ok, so far:

Recent LS2 conversion. (Courtesy of Toro's conversion kit).

Boost leak tested:
Found a nice cut on the boost controller line coming from the compressor housing. Fixed that and idle is sounding better.

Also checked codes:
Got 21 and 54.
21 Ignition circuit. Im presuming this should be disregarded due to the conversion?
54 Auto signal to ECU?

It is seeming that the ecu is jumping into limp mode and just dumping fuel as soon as i touch 10-11psi. Is this a result of a faulty knock sensor?

[Skym]

The stock ECU should engage a rev limiter around 5000rpm when knock sensor fails. Also knock sensor error code would pop up on engine ECU.

I would think the knock is due to something fuel related (fuel pump, fuel pump FPR or wiring to fuel pump) or ignition related (CAS not set correctly).

Do a fuel pressure test to check if fuel pump, FPR is working. Then get a timing light and make sure CAS is set correctly. If the car is converted it could be using the auto 20 degrees BTDC for CAS instead of the manual 15 degrees BTDC.

[ToroGTS]

It's unfortunate to here that a coil conversion didn't provide the silver bullet for this issue. The ignition circuit code is not normal after the conversion, I would look into that more. This is a very confusing issue. I can't say I've ever seen anything similar.