Engine bogging down with any swift throttle change

[Rotary Evolution]

condensation is normal so i wouldn't exactly say that the spray from the exhaust is a problem but just that the engine isn't warm yet.

standing at the front of the car looking at the engine the mark on the driver side of the pulley is the leading yellow mark, the one to the left is the trailing red mark. the engine MUST be idling below 1k RPMs to set timing otherwise it will advance and not be set properly.

warm up the engine and idle it down to 1k or less(you will hear the engine begin to labor and smooth out when it is in idle mode which turns the engine under base timing until it jumps up off idle), jumper the initial set coupler(not really necessary but it will disable the BAC valve which may hold it above 1k). hook up the timing light to your lead #1 rotor plug, adjust the CAS so that the closest yellow mark lines up with the pointer and lock the CAS. move the pickup to trailing #1 plug wire and it should line up with the far red mark.

to test the TPS, hook a DVOM black lead to battery negative, positive red lead to a small pin jammed into the green wire off the TPS. adjust the screw so that the TPS reads 1 volt with the engine warm and idling at approximately 750-800RPMs.

do a sweep of the TPS with the key on/engine off/engine warm, slowly open the throttle to 1/3 and it should read approximately 4.6v and not have any jumps or drop offs in voltage while doing the slow sweep.

if the idle is being problematic and won't idle down to under 1,000RPMs with the engine fully warm then the thermowax is either stuck open due to an air pocket in the cooling system, is stuck due to age, or the idle air bleed screw needs to be turned in. do this first before anything else, sorry for putting it last.

TPS issues/adjustment and timing are the usual causes for off idle stumbles but it could go deeper to a fuel system problem or a vacuum leak.

if the noise you are hearing when romping on the throttle is a pinging sound, like a ballpeen hammer rapping on a sheet of thick metal rapidly then the timing is too far advanced. your timing pulley on the engine may also not match the hub on your engine if it was ever mixed up before during a rebuild. this is usually distinct in that the engine usually kicks back randomly when trying to start the engine. if this is the case then fix it now or the engine will be short lived as soon as it sees boost.

severe advance knock sounds like you're hammering on the engine with a sledge hammer once and then fades rapidly as soon as engine RPMs come up, when you stomp the pedal off idle.

[RETed]

Originally Posted by Rotary Evolution

on some cars even with a standalone on turbo engines i have seen 2-3psi fluctuations even locating the source line at the port i mentioned near the throttle body,

I've never had a problem with this, especially with Haltech systems.
I blame this on a badly tuned fuel map (at idle).


-Ted

[RETed]

Originally Posted by JustJeff

I didn't get a close enough pic, but it's moisture with soot. I tasted the moisture and it's nothing but water...no coolant. Where is the moisture coming from? Is all of that from condensation in the exhaust?

Wow, you're crazy!
Did you type "tasted"???

Don't worry about it until the engine is properly broken in.
Low compression + blow-by tends to spit all kinds of weird stuff out the exhaust.
Couple this with the car sitting around for a while, stuff gets built up in the exhaust...


-Ted

[Pete_89T2]

Originally Posted by RETed

It's odd that it'll affect the RTEK...
The stock ECU uses on open-loop process for idle, so I would think it would ignore the boost sensor signal.

-Ted

That's true, what I meant to say was that the MAP sensor readings we saw in the Rtek logs were noisy even at idle; idle itself was smooth and steady. When doing the baseline dyno pulls, we couldn't get consistent HP & torque numbers from pull to pull, so after checking the logs, it became obvious that the noisy MAP sensor readings was the cause, and the restrictor pill solved that problem.

[Rotary Evolution]

Originally Posted by RETed

I've never had a problem with this, especially with Haltech systems.
I blame this on a badly tuned fuel map (at idle).


-Ted

how does a poor fuelling map translate to 2-3 psi fluctuations at 10-15psi @ 11:1 AFRs? note i mentioned it wasn't a common problem but something i have noticed before on a few cars. if the cars were misfiring due to overly rich conditions in the sub 10's i would tend to agree.

[JustJeff]

Originally Posted by Rotary Evolution

condensation is normal so i wouldn't exactly say that the spray from the exhaust is a problem but just that the engine isn't warm yet.

standing at the front of the car looking at the engine the mark on the driver side of the pulley is the leading yellow mark, the one to the left is the trailing red mark. the engine MUST be idling below 1k RPMs to set timing otherwise it will advance and not be set properly.

warm up the engine and idle it down to 1k or less(you will hear the engine begin to labor and smooth out when it is in idle mode which turns the engine under base timing until it jumps up off idle), jumper the initial set coupler(not really necessary but it will disable the BAC valve which may hold it above 1k). hook up the timing light to your lead #1 rotor plug, adjust the CAS so that the closest yellow mark lines up with the pointer and lock the CAS. move the pickup to trailing #1 plug wire and it should line up with the far red mark.

to test the TPS, hook a DVOM black lead to battery negative, positive red lead to a small pin jammed into the green wire off the TPS. adjust the screw so that the TPS reads 1 volt with the engine warm and idling at approximately 750-800RPMs.

do a sweep of the TPS with the key on/engine off/engine warm, slowly open the throttle to 1/3 and it should read approximately 4.6v and not have any jumps or drop offs in voltage while doing the slow sweep.

if the idle is being problematic and won't idle down to under 1,000RPMs with the engine fully warm then the thermowax is either stuck open due to an air pocket in the cooling system, is stuck due to age, or the idle air bleed screw needs to be turned in. do this first before anything else, sorry for putting it last.

TPS issues/adjustment and timing are the usual causes for off idle stumbles but it could go deeper to a fuel system problem or a vacuum leak.

if the noise you are hearing when romping on the throttle is a pinging sound, like a ballpeen hammer rapping on a sheet of thick metal rapidly then the timing is too far advanced. your timing pulley on the engine may also not match the hub on your engine if it was ever mixed up before during a rebuild. this is usually distinct in that the engine usually kicks back randomly when trying to start the engine. if this is the case then fix it now or the engine will be short lived as soon as it sees boost.

severe advance knock sounds like you're hammering on the engine with a sledge hammer once and then fades rapidly as soon as engine RPMs come up, when you stomp the pedal off idle.

I've never tested TPS using voltage, I've always done a resistance test. I'll try it your way. Though I didn't understand "with the key on/engine off/engine warm"

A couple things to note, I have a JDM engine so I'm missing a few of the standard USDM parts. I have no thermowax (that is the part sitting on the back side of the TB with 2 coolant ports, correct?) Air bleed screw is on the BAC correct? JDM BACs do not have that screw. What I found yesterday was changing the tension on the throttle cable changed idle RPM. Not sure this is the best methodology, but it worked yesterday.

Pulleys should match as I've only ever worked on S5. So unless a previous owner mucked it up all my pulleys should match.

The noise I hear and bogging/hesitation is when I lightly flutter the throttle. For the most part I can smoothly rise and fall the RPM. It's that swift little start to the RPM going up when it behaves oddly.

Originally Posted by RETed

Wow, you're crazy!
Did you type "tasted"???

-Ted

Haha, I did and I am. Now mind you I did not put a glass under my tailpipe and take a swig. I simply dabbed my finger in the moisture to see if it tasted like anything other than condensation (coolant, oil, gas)

[Rotary Evolution]

yea, the thermowax has a yellowed plastic port with 2 vacuum ports on it although the JDM engines didn't have that piece on it. the thermowax is what connects to the coolant port on the bottom of the throttle body to the rear iron so if it is missing then it must be deleted.

the JDM BAC has no idle air bleed in the BAC so the idle has to be hard set with the throttle stop screw on top of the throttle body facing the passenger side of the car with an 8mm locknut on it.

i prefer the voltage method over resistance because with older wiring you may get resistance within specification but once the wires have a load on them problems arise which is easier to spot with voltage under load than with a resistance method. an auto ranging DVOM will be a little tricky since it usually will auto range once you hit between 2 and 3 volts, causing the DVOM to lose the reading for a split second. you can choose your own range though so it will not auto adjust.

[JustJeff]

Originally Posted by Rotary Evolution

yea, the thermowax has a yellowed plastic port with 2 vacuum ports on it although the JDM engines didn't have that piece on it. the thermowax is what connects to the coolant port on the bottom of the throttle body to the rear iron so if it is missing then it must be deleted.

the JDM BAC has no idle air bleed in the BAC so the idle has to be hard set with the throttle stop screw on top of the throttle body facing the passenger side of the car with an 8mm locknut on it.

i prefer the voltage method over resistance because with older wiring you may get resistance within specification but once the wires have a load on them problems arise which is easier to spot with voltage under load than with a resistance method. an auto ranging DVOM will be a little tricky since it usually will auto range once you hit between 2 and 3 volts, causing the DVOM to lose the reading for a split second. you can choose your own range though so it will not auto adjust.

Thanks for the explanation on thermowax, I do have the coolant port on the bottom and am using it.

From your description it sounds more reliable for me to be setting idle with hard set than by tensioning my throttle cable.

And yes checking voltage does seem more reliable, I assume that using multimeter is the same idea behind using one of the test light tools..only you are looking at actual numbers

I don't know that I'm going to get much work done on the car. Drinking 2 bottles of wine seemed like a splended idea last night, but I'm not very motivated to get much done today.

[vrracing]

My JDM S5 Tii has a thermowax. Here's a picture of it.



and a close up

[Rotary Evolution]

meaning it has no double throttle vacuum port(the yellow 2 port plastic bit). all the throttle bodies have a thermowax.

[vrracing]

Yes, Jeff said he had no thermowax because he had a JDM. My pictures were intended to show him how to recognize it. If he compared the pictures to his setup and didnt really have it, then he'd know someone molested the engine before he got it.

[JustJeff]

Yeah, I always thought the thermowax was only the plastic fitting with the two ports. Thanks for the explanation.

By the way, that is a gorgeous and clean TB. I have a spare one I'm going to tear apart, clean, etc. Do you happen to have a write-up on cleaning and reassemble?

[vrracing]

Anal-retentiveness FOR THE WIN!

It's just cleaned with Oil Eater. It doesnt cause the white scaling like the Castrol SuperClean does and it doesnt burn my eyes when I spray it. After I cleaned it I lubed all the moving parts with Royal Purple Maxfilm.

There are write-ups on the other forum covering powder-coating the TB. I followed them when I cleaned and reset everything. btw, I set the thermowax on the counter using a heat gun to move it thru its paces.

If I take it off again I'll probably paint it with Duplicolor aluminum wheel paint. I painted the XKE's Stromberg carbs with it and they are beautiful. Or maybe not. The TMIC covers it up. The rotor housings are diamond graphite and the irons red but no one can see em!

[JustJeff]

Nice job on the obsessiveness, it looks clean enough to eat off of

I'm planning on getting a few items powdercoated, my spare TB, alt pulley and any other small items which strike me as looking good in black

[JustJeff]

Here's what I've got so far:

I've got timing close, but trailing timing does not line up. Leading is perfect on yellow (white in my case because I powdercoated and repainted the marks) mark, but trailing is off by a bit. It's right around 1/3 of the way between red and yellow.

I tested TPS a few different ways. I tested straight resistance per FSM and did some deadzone. But I see deadzones in every TPS I test in the same general area. I got advice on the other forum about always testing TPS in continuity mode because sometimes autoranging will "timeout" and show OL. Testing in continuity shows smooth figures with no deadzones.

I also tested with voltage as suggested here and that comes up different. I get it set to 1v, engine warmed up, pos lead back probing greed/red wire, neg lead grounded to battery. Idle might be a little higher than 750-800. It was at 900 when I last had it idling and warmed up. I started up the engine to check idle and turn it down a bit and it was perfect between 750-800. I start moving the idle and it reaches about 3.6v and OL and I haven't gotten to 1/3 of the movement. I made a video on my smartphone. I'll upload it once I get home today/tonight.