Having decided to eliminate the selector switches for the digi-dash, (half of them don't work anyway with the '90 ECM) I decided to employ AutoMeter gauges for oil pressure and water temperature, both of which feed the ECM and the dash for certain functions.

It seems the best place for the manual oil pressure is to tee the fitting for the oil temperature at the filter. Any problems, there?

I have not decided on where to grab a temperature feed. The '84 uses two as you know, and one was somehow messed up ( as yet I haven't found exactly how) by the clowns at Sevens Only. So, I am knee deep in trying to find out why my fan runs the moment the ignition is switched on, regardless of conditions and finding out what they did with the knock sensor. I think the dark blue wire for it is connected to the temperature sensor in the right head! I am reading the wiring diagrams and am about to drop the ECM to trace the wire, but.....

The car is an absolute blast to drive; just needs some refinement to get it back to where i had it. [asubtle (a- suu-till) is my new word for it, as I cannot sneak up on, or away from, anyone.]

Should I add a third sensor just for the gauge? If so, where? Mike

 

No problem feeding the pressure guage above the filter. That was the OE location on my C3. Cant help with the rest.

 

the temp sensor on the front of the engine is the one the ecm uses and the temp guage uses. the one in the pass side head is the one that tells the fan when to go on and off. if the one on the head has wiring messed up then chances are thats why your fan isnt working properly. i am uncertain as to the coloring of the wires. perhaps your fsm or wiring diagram from a haynes or chilton will tell you. If you dont have a manual let me know and ill go take a look at mine to see if it does. well i forgot your is tpi and ya might have a different wiring harness then an 84 (which is the year i have) if you know what year the wiring came from should be able to look in that fsm for the color.

 

Thanks. The car is a hybrid and the '84 and early-'85s were uniquely wired that way. Later cars had the ECM switching the fan, but mine was left as stock, until I let some 'pros' work on it. If you read the post, you'll see that Sevens Only screwed up many thing on this car.

The thrust of my question asks for input on how best to get the two analog gauges fed properly, while not compromising feeds to the ECM.

Thanks for the help.

Thanks. I thought I remembered that from my '71 coupe, decades ago, though.

 

The gauges on the '84 were not wired to the ECM. Total removal of the ECM, as in a carb conversion only disabled the MPG feature. All the other gauges work just fine. You seem to know that the '84 was the only year that had NO ECM involvement in the fan operation. The black and yellow wires to the connector at the front of the intake manifold was the ECT sensor for the ECM, ONLY. The fan switch between the #6 and #8 spark plugs in the right side head connected via a brown wire, ck #335. Circuit 335 also connects to a switch on the A/C compressor with a tan wire. Grounding ck #335 at either point closed the circuit to the primary side of the fan relay to switch the fan on. The blue wire connected to the temp sender in the left head, between the #1 and #3 spark plugs is for the IP temperature gauge. Again, no ECM involvement. Any help?

RACE ON!!!

 

Thanks. I was working my way through the wiring diagram, which is not my idea of fun, but necessary. I thought I was 'up' on the temperature senders on the '84, but forgot that there were actually three, not two.

Seems that the best source for the new AutoMeter temperature gauge is that left side hole in the head.

Just to keep it interesting, I guess, the hacks at Seven's Only Racing, pigtailed both head sources and changed to wire colors! that is in addition to connecting the knock sensor wire to the temperature sending unit that is supposed top comntrol the fan. Now, where did that knock wire go?

I am also stuck on where the end of the brown wire goes. Midway in that wire is a flat lug that has a rather large bolt hole; about 1/2". It comes from a loom in the upper firewall area, seems to fit a bellhousing bolt or something, and continues to ?? I am not positive, but the other end may go to the ESC plug on the distributor.

I need to find out what is grounding the wire into the fan relay AND is they lef the thermostat out. I just discovered that there is no coolant, just water in the block. WTF?

Little by little, I get it back to where it was and a bit better.

Thanks for the help, VetteBros.

 

What intake is going on the 409?

 

the PITA SuperRam Accel/Lingenfelter has been on (and off) the car for a few years.

 

right on! have you dynoed or tracked the car yet? not many 409's on the forum.

 

The displacement is an educated estimate as the block is a late '70s 400 block, now 40 over. I love the low end, big-block-like torque, plus it pulls real hard all the way to fuel shut-off at 6300 rpm.

The intake functions real well but causes all sorts off other problems here, like the broken wiper cover, the difficulty getting the distributor and wires just so while properly timed. This time, it took me 3 days to and a pint of blood to dissasemble it. I drilled the holes for the 16 fasteners between the plenum and runners, then used Nylock nuts to prevent bolt/nut loss into the engine. After the first attempt, I learned to be liberal in the application of Permatex black to get the thing sealed.

The guy (1-man shop) to got the car to run well after I put the car together (re-chipped it) is also a longtime Corvette owner/enthusiast. He has 3 or 4 collectibles and tells the straight skinny on mods. How rare is that? His decades of experience with models up to and including heavily modded ZRs wear why this car not only runs, but passed CA SMOG. I am honored and grateflul that he took the time to do it; disproving other 'experts' who said this cam would never allow the car to idle properly or pass smog. Sadly, Gary retired.

So he was the guy who told me this car will smoke any stock ZR-1, calling it a "beast". I had the car dynoed a few years ago and called him, as I thought the results were too low. He agreed, saying that for proper readings, a dyno needs to be calibrated and properly used (like any instrument). I know it was not calibrated.

I know the numbers can be a basis for comparison, but can also be like the size of a guy's, err, watch. I think I'd be better off with lower rear gears than the hardened 3.54s, as I light the 335s at will in 1st; cannot hook them up at all with full throttle. A couple of nights ago, I learned that I have to be careful in 3rd, too, b/c I downshifted to pass, nailed it and the rear end broke loose! How cool is that?!?!? (only b/c the car's suspension/steering reacts like the near-racer it is).

I rarely play much with other vehicles, but am 1 for 1 against big bikes. They guy who puilled away was on the rear wheel, only. Ricers take the relatively stock appearance as an invitation, until they hear the uneven, lumpy idle throught the nasty exhaust, when all eye contact ceases. Perfect!

This is ONE FUN VETTE; the most fun of the seven I've owned! Thanks for the interest.

 

If you call a switch a sensor, than all of the 1984 through 1989 had three for coolant. All L83s and L98s had the ECT sensor (Engine Coolant temperature) for the computer in the front of the intake manifold pointing forward. All 1984 - 1989s had the instrument panel (IP) gauge sender in a head; the right head in 1984 & '85, and the left head in 1986 - 1989. All 1984 - 1985 had a temp switch in the right head. In 1984 it controlled the only fan. In 1985, it was a back up to the ECM for the main (only) fan in cars without an aux fan, and the non-computer related control of the aux fan in cars with the B4P optional aux fan. That switch swapped sides with the gauge sending unit in 1986 and was only present in 1986 and up cars with the optional (B4P) aux fan, and therefore, it became known as the auxiliary fan switch. Cars (1986-1989) with no aux fan cars had a plug in the right head.


That makes sense.


The dark blue wire from the knock sensor goes inside of the loom directly to terminal "E" of the ESC module mounted near the heater blower motor.


That sounds like the brown ground wire from terminal "D" of the same ESC module on the heater blower motor housing. After the eyelet there should be a tan, slightly smaller wire that goes into the harness. It connects to terminal #15 of the black, 22 terminal, ECM plug.


The proper brown fan relay ground (ckt #335) wire runs from the fan switch in the right head to a 17 connector plug. From the other side of that plug, ckt #335 is a dark green/white wire that runs to a 29 terminal plug. Coming out of that 29 terminal plug ckt #335 remains in a dark green/white wire that runs and connects to terminal "B" of the fan relay.


Good luck, and...

RACE ON!!!

 

Perhaps that is more airplane lingo, but they are sensing temperature and some are switching things on and off. I suppose more desciptive terms would fully describe one as a switch, anothers, of variable resistance, sensors or thermistors.

I appreciate your taking time to share the knowledge and the clarification of terms.