Sorry, I know TBI needs manifold heat. I should have made clear that i meant MPFI doesn't need manifold heat. I am sick as a dog with some kind of nasty flu bug right now so I apologize if my posts aren't exactly clear.

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Casually looking for a Clifford hyperpak intake for cheap.

You too Reed? Hopefully it's not what I have: it hit like the flu, but after a couple of days it morphed into a cold. Now it's a week later, the phlem isn't bad, but the fact I need a couple of naps per day to get through the day is getting old... That and the fact that it's going onto ten days now.

Interesting stuff Dan. I'm wracking my brain, trying to think of all the TBI vehicles I've been in. And I can only think of dad's '87 Astro. TBI just wasn't around long enough... Anyhow, I don't remember any real issues with it. In the coldest of weather it would just start up (coastal Maine, so, relatively cold). I don't recall that 4.3L ever having cold running issues, even w/o letting it warm up--just a flat spot off idle once it got a bazillion miles on it. We always blamed that on the TPS, though.

Then again, it never did better than 18mpg. Barn door aerodynamics or a rich-running engine? It was heavier than you'd think (other side of 4k from what I've read ); but with 4.3L/AOD/low 3's for a rear end you'd think it could do better. It also wasn't fond of downshifting out of OD, which wasn't helped by the flat spot. I know the later Vortec 4.3's with whatever version of MPFI they had did better mpg's and power.

I had a '91 ex-police Chev Crapiece(!) with TBI 350. Same setup as your '87 4.3. It had fine driveability until all the sudden it didn't; until the engine was well and truly hot it gasped and stumbled and surged and got lousy gas mileage. It turned out to be an olde-tyme problem: the flexible stovepipe duct from the exhaust manifold heat stove up to the air cleaner snorkel had fallen off and hit the road, so no more heated intake air. A new stovepipe fixed the problem immediately. Similar symptoms when the manifold heat control valve ("heat riser") failed and was fixed on my '89 TBI 318 Dodge truck

Agree on MPFI not needing a heated intake manifold, but some MPFI systems have had thermostatic air cleaners. IIRC my sister's '90 VW Jetta with KE-Jetronic MPFI had a thermostatic air cleaner that failed (like many other parts and systems of that pathetic excuse for a car) and caused driveability problems til it was fixed.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hope y'all feel better soon. Hope I don't catch whatever's going round!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Make sure to sit back Dan, or you might catch it through your monitor!

Anyhow, that's an interesting diversion for this thread. If one does a TBI setup, they likely will want to retain these heat riser bits. And if one is doing MPFI for the interests of high mpg's (as opposed to high output power) -- they likewise may want to retain these parts. Or at least experiment with using them, before tossing them, to see if they offer any mpg advantage.

I didn't see that going into this thread. I was thinking all those heat bits could go away with any form of EFI.

Interesting bit about the MPFI using heated air intake. I have only ever really messed around with the 89-93 Ford MAF based MPFI system, but it has absolutely no provision for heated air in the intake whatsoever (unless you count the EGR valve, but I doubt Ford used the EGR system as a source for heated air for cold startups).

TBI really can be thought of as a highly controlled feedback carburetor. The same fuel distribution, fuel settling, and carb icing problems that happen to carbs happen to TBI systems.

MPFI doesn't have these problems since the intake manifold is "dry" (just air, no gasoline/petrol) and the fuel is injected right at the back of the intake valve. Cold engine driveability is controlled by the O2 sensor and the fuel enrichment vs. engine temp table in the FI computer.

First my oldest sister got sick, then my Ma got sick, then I got sick, and now my younger-older sister is sick. It really sucks. I'm just glad we don't have guests for Thanksgiving because (a) we would get them sick and (b) I don't think I could deal with sitting upright, much less making polite conversation, in my present state.

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Casually looking for a Clifford hyperpak intake for cheap.

Here are my thoughts:

1. Lou Madsen, Dart 270 has had more success with his EFI than I have. He just talks about it less. He has run a TBI set up on his 64 with good results that could be improved upon only slightly with MPI. Get him to talk a bit if you can.

2. The hardware is the easy part. Fuel rails and manifolds can be machined by any competent machine shop. There are outfits who specialize in this. GM sensors have become the default for most aftermarket system.

3. The ECU style and manufacturer and the tuning are the hard parts.

4. Fueling is the easy part to make work. Ignitions get complicated real fast. I still do not have mine free of unwanted stray feedback of some kind. I think the rewards of getting the ignition to work are not as great as the payoff from fuel. The most bang for the buck would be MSII fuel only.

5. Evenutally the lap top is a pain. Getting it out and hooked up, and opened to the tuning program and talking correctly to the ECU takes time that you will eventually resent. The FAST system has a small, hand held tuning device for tuning, and has a self tune feature that makes it seem really appealing. I would consider this system after doing your due diligence and reading all the reviews you can find.

6. Was it worth it? Maybe. I have never gotten as good a mileage as I got when the car had a simple BBD carter 2 bbl. I got a high of 29 MPG on one full tank of highway driving. The tests I have run so far on this set up show 23 MPG highway. Drivability is way better than with a carb. It is fun to watch the AF ratio as I drive, but of course you could do that with a carb as well. Although with a carb, it is much harder to change it if you don't like what you see.

7. The fuel tank is a challenge. The surge tank thing will work, but nothing beats a modern in tank fuel pump. Eventually you may end up there as I did.

8. Read-read-read, and more read.

Don't hesitate to ask specific questions as you get into it. We will be happy to help.

Sam

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Multi-point (or sequential better yet) is the best EFI system around. The new direct injection systems are not that great- lots are having BIG carbon buildup problems on the intake valves- there's no fuel spray to "wash" them off.

Many "modern" systems no longer have intake air heat. (Volvo is the only holdout I can think of- ahh, those Swedes). There are quite a few that still have coolant passages going through the throttle body. Some cars now have heated PCV valves!

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63 Valiant Wagon
225 - 4 bbl

Errrr…cite, please?
Wow, haven't seen that. Which?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm looking for a direct cite; am googling "direct injection problems".

From what I've been told it's related to engine shutdown. The last cylinder to fire doesn't necessarily exhaust out the exhaust--instead, it can leak back into the intake tract. On a port injection (or carb) motor, the fuel injection event provides some raw gasoline to wash any crud off. A DI motor OTOH has nothing of that sort; any crud that got spit out in the intake (again at shutdown) will settle back down, cool, harden, and cut airflow. [Crud as in partially burnt hydrocarbons.]

http://forums.audiworld.com/showthread. ... rbon+build

http://www.m3post.com/forums/showthread.php?t=258516

http://blogs.insideline.com/straightlin ... -true.html

I'm not finding much at the moment; perhaps it is (was?) a teething issue. Don't have a GDI so I have not kept up with the issues.

Found this link today:
http://www.rowand.net/Shop/Tech/SlantSixTBISwap.htm
which goes into some depth about using adapters for getting the GM 4.3L TBI onto a Super Six intake. Might be of value for that aspect.

Here's the initial "blurb" from a trade magazine at work.

http://motorage.search-autoparts.com/mo ... =&pageID=1
There's a tasty valve pic on page2.
Not much by itself, but when I google "direct injection valve deposits" I find lots of posts & pictures. If I can, I'll dig up some TSB's for specific cars when I have some free time at work.

I would suspect that much of DI carbon buildup is from normal pcv/crankcase fumes. These fumes settle out after eng shutdown & bake on during the next run cycle- esp on the HOT intake valves (they don't have fuel spray to cool & 'wash' the backs of the valves.)

Heated (hot water or electric) PCV valves can be found on many late model Fords, esp vans & trucks with V-6 eng like 3.9L & 4.2L.

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63 Valiant Wagon
225 - 4 bbl

That's interesting; the crankcase fumes that is. I know that VW TDi's had a horrific problem with intake manifold plugging. The crankcase fumes would mix with soot from the EGR, and could plug up an intake manifold. [The fix? driving harder (to "blow out the carbon" plus ultra low sulphur diesel fuel.] But if it was purely crankcase fumes, then a lot of diesels would have intake valve deposits too.

Not saying that crankcase fumes don't have an impact, I'm just not sure how that jives with diesel engines.

How does that jive with diesels? Simple- until very recently, diesels were not required to have (closed) pcv systems. (for example, Ford 6.4L diesels do have a closed breather system, while earlier 6.0L & 7.3L have no listing) I'm not sure about current requirements, as there have been so many changes in diesel emissions controls during the past few years that I can't keep track.

I don't know what the difference in "fume composition" would be between a gas eng vs diesel, and whether that would affect carbon buildup.

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63 Valiant Wagon
225 - 4 bbl

One other note on GM TBI - they didn't run an air temperature sensor on most TBI applications. While their multiport setups could detect a change in air temperature and compensate by adjusting the mixture, having a TBI lose its intake heating means you would see more air than the factory ECU accounted for, and it would run lean. I can't recall if the Mopar TBIs had an air temperature sensor or not.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair