When Well Enough Can't Be Left Alone; Backdate, EFI/ITB, AC, and more!

[Showdown]

Day 7

One step forward, two steps backward
Down inna Babylon


Yesterday before leaving work I did the following:

Calibrated the TPS
Calibrated the temp sensor
Calibrated the MAP
Replaced intake gaskets with new ones.
Replaced plugs as they were super fouled.

With those done, I was able to start the car almost instantly and get it running albeit choppy and inconsistently. It even held idle. IT HELD IDLE. The MAP signal was super high though. I grabbed a nice long datalog to scour over and send to Al. Then I went home feeling great.

This morning I woke at an ungodly 3am and couldn't get back to sleep so I headed into work to tend to this car.

I was able to start the car quickly but I couldn't get it to hold idle. Sad face. I tried again, and the same thing. I was noticing that I was still getting MAP readings in the 90s which basically means no vacuum signal. Which means a leak, right?

Ok, let's go hunting.

Checked all of the hoses for tears or holes: nothing.
Checked all the connections just to be sure they were, you know, connected: all good.
Checked the manifold and teflon taped all the threads just to be sure.
Disconnected the brake booster hose and plugged that hole.
I even checked the MAP sensor by sucking on the hose to see if it would register a signal: it did.



That said, I had to really suck on that hose- like pulling a milkshake up a straw. I don't know how sensitive these sensors are supposed to be, maybe someone can enlighten me. It seemed like a lot of effort. That said, it did respond so, I dunno.

I tried again to get the car to run without giving it gas... nope.

I tried smoke test the ITBs but I have no idea what I was doing so I'm sure I did it wrong. Perhaps someone can tell me the procedure. I taped up the top of the ITBs and pulled the vacuum hose from the manifold and attached the smoke machine to it. I was looking for leaks at the gaskets but didn't see any. I saw some leaks above the butterflies but those shouldn't matter. There were also some leaks around the butterfly shaft.

So after all of that I couldn't even get the car to start let alone hold idle. So I pulled the plugs, and yup, they're fouled...again.




So I'm now stuck in a cycle: get new plugs and the car will start and hold idle but that will begin the process of fouling the plugs because the MAP signal is too high in the VE table and dumping tons of fuel thinking I'm at WOT and I'm not so that fouls the plugs and then I can't get the car to hold idle or even start. And that means that I can't set the timing or start tuning, and I have to buy new plugs...again.

A few questions:

1.) is my assessment of the cycle correct?
2.) where else could there be a leak this big?
3.) is there a way to smoke test ITBs?
4.) Who put the bop in the bop shoo bop shoo bop?

Oh, I cut off the long hood extension I had welded on the hood earlier and welded on a new one...more on that later. ugh.

[Showdown]

You know that moment when you suddenly think of something that may both solve your problem and make you look like a royal doofus...

I just realized that the intake gaskets that I've been using are the CIS ones for my 2.7 with the injector cutouts.

I'm guessing I need something like this instead:

https://www.clewett.com/index.php?main_page=product_info&cPath=4_48&products_id=330

[al lkosmal]

Julian,
you set initial timing ...at first, statically. I.E.setting the engine so that #1 is at TDC and verifying that the rotor is pointing to the #1 dizzy .......then you use your timing light and the trigger wizard in Tunerstudio, to verify/adjust while cranking the engine over....with the fuel pump fuse pulled.......so that you are cranking over (not running) with no fuel...just ignition...

Once these timing basics are completed, you can then verify timing at idle and verify advance, etc.

I'll email you some directions.....

If you are getting leaks at the manifold gaskets (there are various ways to test this).....the spacer kits from PMO or Clewett work well....although typically not required for the 2.7.... until you get to the 3.2 engines......

[Showdown]

Al,

I knew I forgot to do something today. 3am will do that to you.

Mental note: set static timing, set static timing.

[chrisbalich]

J,

Have you confirmed your MAP signal changes when you rev it?
I'd check out that vac system.
Cap/Plug all the hoses at the TBs, disconnect the brake booster hose and connect a vac pump at the booster nipple. Then check for leaks.
If none, connect your vac pump to the booster hose and check for leaks. The check-valve in my booster hose is a 2pc contraption that separated once and caused a massive vac leak.

Gotta systematically work your way though the entire air system (vac, ITB, intake manifolds) to figure out where you're going awry. There are a lot of opportunities for leaks, so be paitent.



ONE OTHER THING I JUST REMEMBERED
I'm guessing you haven't yet sync'd your ITBs. If one of those bad boys is way open (at idle), it'll skew the MAP reading for the whole engine.

[Showdown]

Chris,

On Friday when It was holding idle and somewhat cooperating, I gave it a few revs just for the lulz and the MAP signal definitely changed:



I haven't sync'ed the ITBs yet. I really haven't done much of anything as I only had it running and holding idle once. Every other time I was stuck in the driver's seat praying.

I do have a vacuum hand pump so I'll go through Each. And. Every. Hose. jsut to be sure there aren't any leaks I didn't catch...

[rwest]

Originally Posted by Showdown

Chris,

On Friday when It was holding idle and somewhat cooperating, I gave it a few revs just for the lulz and the MAP signal definitely changed:



I haven't sync'ed the ITBs yet. I really haven't done much of anything as I only had it running and holding idle once. Every other time I was stuck in the driver's seat praying.

I do have a vacuum hand pump so I'll go through Each. And. Every. Hose. jsut to be sure there aren't any leaks I didn't catch...

You really should synch the ITBs as soon as possible- I found a lot of variation in mine- of course you need a running engine to do it. Do you have the linkage disconnected while running to test that one of them isn’t part way open?

For reference, I’m getting MAP in the low 50s on my PMOs at zero throttle.

Rutager

[Showdown]

Right now the biggest problem is that I can't get it to run and hold idle consistently. So I think I'm limited in what I can actually do until the car holds idle.

Feels very catch-22.

Rutager- did you ever figure out how to smoke test your ITBs. I'm wondering if that might help isolate the source of the MAP leaks...?

[rwest]

No, didn’t figure out a great way to test mine, in fact it seemed like maybe my valves were leaking because it didn’t matter where my crank was, I was getting smoke out of several other stacks- and as I just wrote this, I realized that my vacuum lines all go to a common vacuum block, so of course the smoke would come out of multiple stacks- duh!

I’ll try again with each line blocked and valves to that cylinder shut. I also wonder if you got plugs that fit in each trumpet and sent smoke up the tailpipe if that would test them all with a few turns of the crank to open valves?

I’m also using an IAC and Al had me take my MAP off of 2&5 directly and the other cylinders get fed the idle air when open.

Since you have a vacuum tester, maybe put it on each throttle as it runs and see what the vacuum is?

[Gabe.]

Originally Posted by chrisbalich

J,
ONE OTHER THING I JUST REMEMBERED
I'm guessing you haven't yet sync'd your ITBs. If one of those bad boys is way open (at idle), it'll skew the MAP reading for the whole engine.

This has been fun to follow along!

I was sitting here thinking the same thing Chris mentioned, did you sync your ITBs yet? You might also want to grab some more vac line and run one out the engine bay to wherever your ECU/Map sensor is to make sure there are no kinks (there may be some sharp bends if you ran it through the shift rod tunnel).

Chris, you should just head up to Chicago and help out one of these Saturdays

As for continuously fouling the plugs, you can get a spark plug cleaner from harbor freight to save yourself some funds if you have an air compressor: https://harborfreight.com/pneumatic-spark-plug-cleaner-32860.html?_br_psugg_q=spark+plug+cleaner

The advice from everyone else has been great. Be methodical, read through the start-up guide in the manual, and you'll get there. You'll also learn a hell of a lot about how engines and modern EFI work. It's fascinating.

[Mr Beau]

Make sure to turn off any O2 correction. If you have a rich misfire, the O2 sensor sees it as being lean, and adds more fuel, making the issue worse.

With that said, your log shows it running pig rich off idle. Bad intake gaskets wouldn't cause this so seems like you more of a tuning issue.

Should be easy to lock your timing and verify with a light. Turn off ignition idle control initially so you don't chase your tail.

Post a log(s) with as many channels as possible. Could be an enrichment setting too.

[chrisbalich]

Originally Posted by Gabe.

This has been fun to follow along!

I was sitting here thinking the same thing Chris mentioned, did you sync your ITBs yet? You might also want to grab some more vac line and run one out the engine bay to wherever your ECU/Map sensor is to make sure there are no kinks (there may be some sharp bends if you ran it through the shift rod tunnel).

Chris, you should just head up to Chicago and help out one of these Saturdays

As for continuously fouling the plugs, you can get a spark plug cleaner from harbor freight to save yourself some funds if you have an air compressor: https://harborfreight.com/pneumatic-spark-plug-cleaner-32860.html?_br_psugg_q=spark+plug+cleaner

The advice from everyone else has been great. Be methodical, read through the start-up guide in the manual, and you'll get there. You'll also learn a hell of a lot about how engines and modern EFI work. It's fascinating.

All of this.

And after I get my truck aligned and install the new tires this week, I can probably make a trip up if you'd like a second set of hands & eyes. Can't bring my 911 for reasons I'm about to divulge in my own build thread. Well, that and totally insufficient heat for this weather.

[Showdown]

This morning I got to work a bit early (and ignored the mountain of stuff I NEED to do) and spent some time with the car and tried to locate the air leak that's killing me.

I readjusted the butterflies so that at rest they're fully closed- as closed as I can get them.

I set the timing, or started to; I have the rotor pointed at the #1 notch with the crank at Z1. It was off a bit; hopefully this little adjustment will make a big difference.

All the plugs got pulled and cleaned with a brass brush and acetone... they look pretty darn good now.

I tried to isolate every part of the ITBs and find the air leak but without a running engine it's really hard, maybe impossible.

Here's what I have done:

- Sucked on the brake booster hose; it provides solid resistance but it's not air tight

- Sucked on each ITB hose; they each provide good resistance but are not air tight.

It should be noted that when I say that they provide resistance, imagine the sucking force needed to get a milkshake up a straw... I tried to use my little handheld vacuum pump but it was worthless and didn't register any vacuum (is the engine supposed to be able to hold a vacuum when not running??). When I assemble the manifold and suck on it the resistance drops to almost nothing and it's like free flowing air.

With that said and done, I'm hesitant to try and start the engine up and foul my plugs again.

I had an idea, probably a stupid one but one nonetheless.

Create a false vacuum signal to the ECU with the handheld vacuum pump, 50kpa is about 15inHg and the handheld can do that. That will simulate a good vacuum signal at idle and hopefully get the car pushing the right amount of fuel, not running stupid rich and holding idle which may then allow me to synch my ITB's and set my timing and measure the vacuum on each ITB and use some starter fluid to isolate the leak(s).

Other than that I really don't know how to find the leaks.

[chrisbalich]

J,

The butterflies in your ITBs don't seal tightly enough to generate/hold vacuum. If they did, the car wouldn't run when you're off-throttle.
As such, you won't be able to check the vac system with it connected to the ITBs. You have to check the system independent of the ITBs and then connect it all.

I still think your 'air leak' is most likely due to poorly sync'd ITBs. One that's too open will destroy the vac signal for the lot.

You can circumvent the system completely and just connect the MAP to one TB. Disconnect the brake booster and the vac manifold and get it running. That should get you running well enough to sync the ITBs.

[Jonny042]

I'm actually just catching up on this thread and really enjoying it.... I can see why it's often on the front page!!! Thanks for sharing, I know it's a lot of work to document the happenings but some people (and you know who you are, Chris) are really good at it and make it entertaining. As they say, SUBSCRIBED.

I pre-synched my ITB's (the bored-out factory ones on my MFI motor) using a shop vac and the synchrometer. It turned out really well. Get 'em all close and then tweak them all at once if needed until you can do the synch properly with a smooth running motor.

This is going to come across as flippant and arrogant, and I really don't know, 100%, if I'm right. So let's call it devils advocate: why not unplug the map sensor and just run it on the TPS? I may prove myself wrong one day, but I don't understand why everyone is beating their heads against a wall trying to get a decent MAP signal from ITB's. I just don't see that it's going to happen.

[Showdown]

Originally Posted by Jonny042

why not unplug the map sensor and just run it on the TPS? I may prove myself wrong one day, but I don't understand why everyone is beating their heads against a wall trying to get a decent MAP signal from ITB's. I just don't see that it's going to happen.

Because all the cool kids do it this way...?

You're asking proper questions that assume I know a lick about what I'm doing here. If it wasn't already crystal clear, I'm flying by the seat of my pants, laying track as the train rolls and hoping that if I fake it long enough everyone will think I've made it!

----------

I got home (and ignored all the stuff I NEEDED to do like feed my kids, take care of the dog and pay attention to my wife [seems to be the trend today]) and did a bit of reading on ITBs and MAP vs Alpha-N.

Again, I don't know anything but from what I gathered your question Jonny is a ridiculously good one and the consensus of the Great And Powerful Interwebs is that trying to run MAP with ITBs is a fools errand, particularly for street cars.

At idle the MAP signal is going to be super noisy with ITBs and even more-so at startup, which is why Motec and Infinity use a hybrid system that starts with alpha-n and then switches at some point to MAP. But even then it seems that at 40% throttle the MAP signal will be like 90+ and not likely to change all that much at WOT.

It seems the benefit of MAP is when there are lots of altitude changes and the atmospheric pressure is fluctuating a lot and the ECU can't rely on assumptions of programmed curves. But again, the ECU is smarter than me and can get a barometric reading and earn its keep with some maths and correct for that.

I still think I'd like to give it a try because, I don't know, something about easy just doesn't appeal to me (um, title of this thread...) but Al did bake me up an alpha-n tune for my car and I have that in my pocket if I need.

I really wish I would have synched my ITBs before I installed them.

[chrisbalich]

Originally Posted by Jonny042

...
I pre-synched my ITB's (the bored-out factory ones on my MFI motor) using a shop vac and the synchrometer. It turned out really well. Get 'em all close and then tweak them all at once if needed until you can do the synch properly with a smooth running motor.
...

This is bloody brilliant.

[Jonny042]

Originally Posted by chrisbalich

This is bloody brilliant.

It didn't feel so brilliant at the time because I used almost a whole roll of vinyl electrical tape to make an adapter between the small vacuum hose and the throttle body bore.

I believe they call this additive manufacturing these days.

It did work pretty well. I just got all the throttle plates closed as tightly as possible and then started with the bleed screws 2 full turns out and started from there. I went for balance over an outright number.

[Jonny042]

Back to the topic/rant of trying to get a clean vacuum signal from individual runner manifolds. I don't ever remember seeing anybody other than Porsche flat 6 people trying to do this. Go look at all the rest of the ITB setups in the world it just isn't done..... is it? Some 911 guy must have done it once and then it just became the way to do it?

Every time a cylinder is on the intake stroke is produces a vacuum on the one hose which is then going to try to build up vacuum in the vacuum manifold, but the five other cylinders are sitting there keeping it from happening, no differently than when you are trying to pull a vacuum with your tester.

I think it's also going to make things even tougher to get a decent signal if you're tying the brake booster into the manifold as well, especially without a check valve. The booster should be off a single manifold runner so you get the highest peak manifold vacuum to the booster. This is how individual throttle carbs have been working for years. PMO manifolds (including those supplied for EFI) come with a threaded fitting and a check valve that goes into one of the runners.

Don't worry, you aren't going to somehow run that one cylinder lean or rich and foul a plug, the path is a deadend and once vacuum is built up in the booster that's it - it's stored until you hit the brakes, that's why you can stop your car once when the motor stalls.

Now, I know people are running cars successfully using map for load sensing on ITB's but honestly I don't know how. I know JPnovak is on his project Minni and I'm not going to claim to be smarter than him.

Like I said I'm more than willing to be corrected and may well eat my words..... I'm going to be performing an ITB install on the Rot Rod and don't plan to have any sort of MAP sensor other than Baro. I'll correct for baro and IAT, both of which are pretty simple, and do warmup enrichment on CHT and leave it at that. For all the same reasons the map signal doesn't work I don't plan to run an IACV, either. Once the idle speed is set and the ITB's are synched I don't see the need for that.

[trond]

mine is running fairly good on MAP but important to NOT have acc enrichment off the map signal otherwise engine will drown in fuel because as you said MAP signal is not a flat line.. AE has to be off TPS or switched off completely. I will try with TPS as well

If firing order is OK and all plugs are firing I would disable AE and O2 correction and reduce fuel significantly in the VE table to get it to run. Using MAP to start with. Worked for me