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90 burb cruise questions

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black dawg

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When I converted my 90 burb to 454, the prom that I used was marked 7.4 3spd no cruise. Is cruise really in the prom?

I have the cruise parts to put on the engine, and have been thinking about doing it, but wondering if it will work without the correct prom.
 
black dawg said:
When I converted my 90 burb to 454, the prom that I used was marked 7.4 3spd no cruise. Is cruise really in the prom?

I have the cruise parts to put on the engine, and have been thinking about doing it, but wondering if it will work without the correct prom.
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If it's fuel injected yes you need the option in the ECM
 
Not real familiar with the '90-91 setups, but how is the ECM and cruise tied together?

My understanding is that the cruise and ECM stayed separate for quite awhile, the only components they share being the DRAC and VSS on the trans/t-case?
 
I guess I assumed since this prom was marked no cruise, that crise control was in the ecm.

Got it all hooked up,and works great
 
dyeager535 said:
Dang, you work quick. :) Good job!
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All that I had to do was adapt the 350 vacuum servo to the big block and work over the linkage.

It is really nice to have cruise with this thing, I would always end going too fast without it. Best 20 minutes I have spent on this burb,
 
I used to hate anything that added electrical or mechanical complexity. But I've come to embrace things like cruise. It really does suck driving long distance without it.
 
dyeager535 said:
I used to hate anything that added electrical or mechanical complexity. But I've come to embrace things like cruise. It really does suck driving long distance without it.
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Tell me about it.
I now drive 11 hours a day and without cruise I wouldn't make it
 
if your prom was marked no cruise it means it came from a truck that did not origanally have cruise so there for you wont have cruise until you put the right prom in my freind had the same issue when he put fuel injection on his truck and it was the prom
 
I guarantee you there is nothing in the prom for cruise control!

The only reason I can think of the prom was marked no cruise is no Lean Cruise?

Cruise control uses a signal from VSS through DRAC. Nothing to do with ECM or the prom/chip.
 
I'm guessing it was marked that way because whoever pulled it didn't know better.

I remember going to one wrecking yard who marked all axles open or posi....all the gov-lock ones were marked "open" because they didn't know how they worked. :)
 
eagle mark said:
I guarantee you there is nothing in the prom for cruise control!

The only reason I can think of the prom was marked no cruise is no Lean Cruise?

Cruise control uses a signal from VSS through DRAC. Nothing to do with ECM or the prom/chip.
Click to expand...

Good to know.

Seems like it would be more logical to have the ecm do it all.

On the lean cruise deal, how much mpg does it usually gain? Also, what conditions does the ecm have to see to enable it?
 
Much newer PCM have some cruise parameters. Remember these old are like a miniature PC with DOS...

Lean Cruise is good for 10 to 15% MPG, my stock 2wd 1990 Suburban is getting 18 to 19.5 MPG highway.

It's a patch that needs to be applied to bin file, then has a temp to enable, MPH to enable, seconds to enable and a MAP setting to disable if load becomes to great.

Rigs with big tires, no gearing, super heavy, stock motors it can have no help and actually be a hindrance. All depends on circumstance?

Big Blocks in general can see big benefits from timing alone. But since most came with no knock sensor the timing is very conservative and set for safe for hauling loads! I've seen a few hurt there motors with aftermarket chips that use a 454SS spark table... then haul a load.... the 454SS PCM was much different and had a knock sensor, better gearing, better transmission...
 
This burb is 3.73 geared, with short tires, and usually turns 23-2600 on the highway. Doesnt feel like the motor is hardly working, very little peddle. So far 12ish highway mpg.

What gearing is your burb? My 2 wheeler 1500 burb with a 350 and 700r4 would do 15 in town and 20 highway. It was geared 2.73 and I drive pretty slow, 65 or less. I bought it geared like that, and figured that it would hurt mpg. It had no trouble holding overdrive even on hills at 60-65, but if you tried to go 70 you could feel that it was taking alot more pedal, and mpg would go down.
 
Your BB could definitely benefit from Lean Cruise. 12 is good from a BB to start!

Your SB could benefit as well, until hills would need Drive instead of OD...

My Suburban is factory 3:73 gears, speedo and odometer are accurate still accurate. This is always an issue when people calculate MPG.

With 3:73 gears I normally pull most hills in OD and still stay in Lean Cruise, it's set to kick off at 75 MAP.
 
anybody know of a source for good diagnostic info for this cruise system? It has never worked right, and now it doesnt work at all.
 
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