The car: 1988 Formula...
I had a 4.9 engine/Transmission from a 1994 Caddy Deville installed.

1) After driving it I asked whats up with the oil pressure gauge?
Come to find out that the 4.9 idles at less than 8~10 psi.
Which causes the oil light to come on at idle.

2)Now my tach is wrong?

3)Also the speedometer is saying 80mph when I'm only doing 73mph (so says my GPS)

Other 4.9 swappers have this same problem..
Anybody out there have any way to fix these problems?


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Life is but a game.
The one with the most toys at the end wins

[This message has been edited by 88_4mula (edited 05-04-2010).]

Do a search here on Pennocks for "My 4.9 wiring thread" by 'Mickey Moose'... I cant paste links here from my cell sorry... It has TONS of information...

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SMTHGT.....
Aka. "SmoothGT"
<---RIP
1987 GT 4.9L~V8~4T60E
(Un.Su.)

Jgunsett here worked my tach over so it would display correctly. I don,t know what to tell you about the speedometer. Several have mentioned the low oil pressure. Go up one viscosity rating of motor oil.

[This message has been edited by josef644 (edited 05-04-2010).]

i have no clue about the oil pressure thing.. i dont know 4.9's at all.. But for your speedo problem, do you have larger rims and tires on the car than stock? That can give you a "off" speedo.. I went from the 14" wheels with 205 tires, too the 15" wheels with 215 tires, and my speedo is 3 or 4 mph off.. So when it says im goin 54, im really goin 50.. So if you have 16", 17" or bigger, that could be the cause of the speedo..

Oil pressure should not be that low. Obviously you would have noticed leak. Make sure you have the right oil filter first. There is a wrong one that is used on the 60 special from what I have found out. What weight oil you using? May need to drop the oil pan to check the oil pump strainer. Could be other things also.

Tach needs to be modded for a V8 (really anything other then 4 or 6cyl). Parts are cheap and its easy to do.
http://www.fieros.de/en/main.html
You need a 200k trimming potentiometer (trim pot, trimmer, ect). Make sure it has 200k resistance. Wire as the page above states. Then dial it in with a scanner when you have one. If you need help just ask.
200k Trimmer

Programmed memcal or VATS bypass? I'm betting bypass and/or the caddy tire size is still programmed into the PCM. Install larger tires, reprogram chip, or just make do for now. I'd go with option 2 if it were me.

[This message has been edited by Fieroseverywhere (edited 05-05-2010).]

The VSS is calibrated for a 26.5" tall tire, same as what was on the donor car.

Send your tach to Jack Gunnset.

No, the correct tires and factory wheels are on the car.
And the speedometer was dead on before the swap.

quote Originally posted by 88_4mula: No, the correct tires and factory wheels are on the car. And the speedometer was dead on before the swap.

your tans is also out of the same car as the motor and the tire size on the cady is differant than the fiero. you will have to see if you can change the speedo gear in the trans. or run cady size tires

quote Originally posted by 88_4mula: No, the correct tires and factory wheels are on the car. And the speedometer was dead on before the swap.

The tires themselves are not the issue. The problem is the constants set in the PCM programming. The caddy PCM has the tire size set for speedo accuracy. Sounds like the wrong tire size is programmed in. The caddy uses a larger diameter tire then a fiero so your wheels (and therefore VSS) are spinning faster then the PCM is expecting. In other words you are traveling slightly less distance then the PCM thinks you are. So your speedo will read high. Its not a big issue really but will require a reflash of the chip to compensate. You don't change speedo gears on a 4t60E VSS, you adjust the chip instead. Its a good thing and allows a much broader range of tire size to be used and more precise speedo reading.

[This message has been edited by Fieroseverywhere (edited 05-05-2010).]

I fixed my oil pressure gauge / light.
It involves adding resistance to the circuit that runs the gauge. I'll get the values for you.
The red oil pressure light is normal in these installations (although a cooler would help.)
I've even seen crate motors do the same thing.

My tach reads 1/3 high. (4500 shows 6K on the tach. ) I bought some resistors to fix it, but haven't done it yet.
The speedometer error is just a reflash, if it's a percentage.

Take the small inspection cover off of your PCM.
Through the top window on the blue Memcal you should be able to see a 4 character code. BWYH, AKYB, or something like that.
What is that code?

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Raydar
88 4.9 Formula IMSA Fasback..........................88 3.4 coupe -soon to be something other than red

Read Nealz Nuze! Praise the Lowered!

[This message has been edited by Raydar (edited 05-05-2010).]

quote Originally posted by Raydar: I fixed my oil pressure gauge / light. It involves adding resistance to the circuit that runs the gauge. I'll get the values for you. The red oil pressure light is normal in these installations (although a cooler would help.) I've even seen crate motors do the same thing. It's pretty much normal.

I never had this problem with mine. I'm using an 88 fiero OPS though so that may make a difference. My oil pressure has never dropped below ~48PSI even when completely warm and in need of an oil change. Curious? When sender are you using?

I'm using an 88 sender as well.

You're the only person I know of who does not have the problem. Seriously.
I'm surprised.

Maybe its the fuel pump relay. I'm using the caddy one unlike most people. It is wired into the same circuit. Who knows. Glad you know a solution. I was a bit stumped because I never had this issue.

The Cadillac aluminum engine runs lower oil pressure than the cast iron engines that we are used to (60 V-6, SBC).

Remember this engine is based off of the 4.1 that had bottom end issues (corrected in the 4.5 redesign, and the later 4.9), and Cadillac went the route of more oil flow and lower pressure.

Flow is more important to engine bearing life than is pressure.

As to the Tachometer error, Jack Gunnset does a very good job in recalibrating the Fiero tach for use with the V-8. You also get a print out of the error at different RPMs and he is very reasonable. He did mine for me last year. He is also a 4.9 guy.

As a note, 245/45X18 tire/wheel combo has roughly the same diameter as the Caddy tire from the deVille. If you are planning to upgrade the rubber on the car, this will correct the speedo error and also fill up the wheel well.

Another note - I also have a Formula with the 4.9/4T60E drivetrain (mine is from a 93 Eldorado), so I understand completely your issues and questions.

[This message has been edited by olejoedad (edited 05-05-2010).]

quote Originally posted by Raydar: I'm using an 88 sender as well. You're the only person I know of who does not have the problem. Seriously. I'm surprised.

Make this one number two. I have not seen the OIL light turn on. The pressure does get lower than I would like to see on the gauge, but the light does not turn on. At start up with a cold engine the gauge nearly pegs. At "normal operating temperature" the pressure drops significantly at idle but anything over idle it goes to "normal" I have not put a gauge on it so I don't know exactly what the pressure is? I use the recommended viscosity that is on the oil cap and I have the factory oil cooler installed.

quote Originally posted by Rickady88GT: ...and I have the factory oil cooler installed.

I suspect that this has everything to do with it.
I've thought about retrofitting mine. It's just way down the list of priorities.

I use 20w50 and run an aftermarket oil cooler (perma cool pn# 691). Pressure never drops below ~48 psi on the dash gauge when fully warm and at idle. Never actually pressure tested mine either. Keep in mind I rebuilt my engine prior to install and the tolerences are like it was new as is the oil pump.

Cadillac oil pressure specs

10 psi @ idle
53 psi @ 2000 rpm

quote Originally posted by Rickady88GT: Make this one number two. I have not seen the OIL light turn on. The pressure does get lower than I would like to see on the gauge, but the light does not turn on. At start up with a cold engine the gauge nearly pegs. At "normal operating temperature" the pressure drops significantly at idle but anything over idle it goes to "normal" I have not put a gauge on it so I don't know exactly what the pressure is? I use the recommended viscosity that is on the oil cap and I have the factory oil cooler installed.

Make mine number 3... pressure drops at idle, but starts to rise w/ little gas petal pressure... AND NO OIL COOLER.. that is something that I will add one later. This is a 91 Seville engine w/ only 32k miles and under 200 miles on the rebuilt 4t60e.

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SMTHGT.....
Aka. "SmoothGT"
1987 GT 4.9L~V8~4T60E
(Un.Su.)

Good thread. Your PCM can be reprogramed to correct for the diameter size of your tires. Your tach can be re-calibrated to fix that problem.

Now for the low oil pressure. The Aux gauges for 86 and 87 are different than the 88. In 86 and 87 the low pressure light comes on at 15 PSI. The 88 gauge is set at 7 PSI. You have the 88 package and you can check the low pressure lamp by removing the connector at the sensor. Taking a 10 ohm resistor and push one end into the center hole (it will be the one for the tan wire), now ground the other end. Now turn the key on and for the 88 gauge package you should see the needle move up about 9 PSI and the low pressure lamp is off. For the members with the 86 and 87 package with 10 ohm the needle will move up and the low pressure lamp will be on, add another 10 ohm resistor to give you a total of 20 ohms and the gauge should read just below the 20 PSI and the ow pressure lamp is off.

The best way is to use a mechanical gauge.

I am also having low oil pressure problems. After 5 year with always having about 15 to 20 PSI when the engine was hot and at idle the pressure has dropped. This last weekend I drove down to the Fiero Factory for the swapmeet. Seem to happen all at once, I lost about 10 or so PSI, I now had to keep the car at 1000 RPM to keep the low pressure lamp is off and when cruising at 2000 RPM my pressure was down about 10 PSI. At least the car got me back to Michigan. I have replaced the sensor and checked the gauge. My next thought is that something has gone wrong with the oil pressure regulator in the oil pump. We are now looking at pulling the pan and replacing it. Will keep you posted.

Jack

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If you can not run with the big dogs, stay on the porch!

Just thought of one other thing to take into consideration for the oil pressure. Most of those who run an auto trans have a lower idle speed set in the PCM. ~600 rpm IIRC. Those with a manual usually have 800 rpm set. This is probably one reason for differences we're seeing.

Hi all, just wanted to report about the oil pressure problem. Removed the pan yesterday (what a pain that was) and replace the oil pump. Things look good, I now have about 20 PSI (hot) at Idle and 40 PSI @ 2000 RPM. I was going to check bearing clearance but did not have enough time. Tip: When replacing the pan gasket use the dry type not the cork. May cost a little more but worth it.

Jack

quote Originally posted by J Gunsett: Hi all, just wanted to report about the oil pressure problem. Removed the pan yesterday (what a pain that was) and replace the oil pump. Things look good, I now have about 20 PSI (hot) at Idle and 40 PSI @ 2000 RPM. I was going to check bearing clearance but did not have enough time. Tip: When replacing the pan gasket use the dry type not the cork. May cost a little more but worth it. Jack

JACK.... may I ask how many miles are on the 4.9..?? I am just curious as when I shoulr check mine as well... Mine has 32k, 4t60e tranny has less than 200 miles. Is there anything else that should be mentioned as a regular item to check around a certain mileage on these Caddy engines..?? Thanks STEVE

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SMTHGT.....
Aka. "SmoothGT"
1987 GT 4.9L~V8~4T60E
(Un.Su.)

Steve, my engine has about 53K on it. Remember I saw a change in pressure that seem to happen from shutting off my engine to the next time I started it. When we got the oil pump out the only thing we found was the pressure relief piston felt a bit sticky, not smooth like the new pump. These engines should run for 250K with no problems, just the oil changes and tune-ups. Remember these engines were designed to 10 PSI (hot) at idle. If you have 10 PSI you are OK. On the oil cooler, you really do not need it but it may help a little in the long run. If you want to install one here is a link on how I installed mine.

http://www.frontiernet.net/...nsett/OilCooler.html

Jack