Speed Density

[88Cam]

I've got a Tpi 88 Cam that I wanna convert from mass air to speed density but I don't know how to.

[TraceZ]

Isnt the MAF system better?

Could you explain your goals? Why would you want to do this, and maybe someone will have an answer.

[Dave M]

try www.thirdgen.org
Lots of guys over there have made the swap and can help you out. They may even have a tech article on the site about the swap.

[Detroit_Bird]

Im kinda curious as to why someone would do this also- I thought mass air allowed you to run a more aggressive cam because of it's improved intake air monitoring.

[Injuneer]

The 3rd Gen Bosch MAF sensors are total "crap".... they flow poorly, they die, the burnoff relay causes problems..... only the new GM design, used on the 4th Gens has the accuracy and reliability to make things work correctly.

[TraceZ]

Originally posted by Injuneer
The 3rd Gen Bosch MAF sensors are total "crap".... they flow poorly, they die, the burnoff relay causes problems..... only the new GM design, used on the 4th Gens has the accuracy and reliability to make things work correctly.

Ahh, yes... burnoff problems. I had those problems in my 88 Iroc 5.7. It sucked. Can a GM MAF from a 4th gen be used instead?

I had another thought, maybe he wants to mount a filter directly to the TB and the MAF is spoiling his plans?

[Dave M]

I had another thought, maybe he wants to mount a filter directly to the TB and the MAF is spoiling his plans?

I'm probably not remembering my 3rd gen days 100% correctly but I believe wanting some sort of ram air effect is the main reason for going speed density. Also, if the engine is moving so much air that the MAf becomes a restriction... could be a reason.

[88Cam]

Yeah basically I just wanna put an air filter directly on and the Maf sensor isn't workin any ways and I'm chisty and wanna see which would be more cost enficient cause I'm broke. Also I don't like the massive amounts of black smoke everywhere I've been gettin since my Maf sensor went out but it passed inspection like that on the 3rd try so all well.

[TraceZ]

Originally posted by 88Cam
Yeah basically I just wanna put an air filter directly on and the Maf sensor isn't workin any ways and I'm chisty and wanna see which would be more cost enficient cause I'm broke. Also I don't like the massive amounts of black smoke everywhere I've been gettin since my Maf sensor went out but it passed inspection like that on the 3rd try so all well.

I'd bet it is less expensive to replace the MAF than to convert to speed density. I'd strongly suggest repairing it.

[Injuneer]

1. A 4th Gen MAF is not compatible with a 3rd Gen ECM. No interchangeability. One puts out variable "volts"... the other variable "frequency".

2. The 3rd Gen MAF is a MAJOR flow restriction, including two "screens", one on the inlet and one on the outlet, and a bunch of internal cooling fins that were supposedly added after a sensor died while GM was testing the car in 140degF Death Valley weather. It is possible to remove both screen and the internal cooling fins and increase the flow capability of the MAF by about 30%.

3. Check with someone knowledgeable in 3rd Gen PCM's. In the 4th Gen, it is entirely possible to switch the stock PCM between mass-air and speed-density. There is full speed-density "default" capability in the event the MAF fails. Might want to see if the 3rd Gen ECM has the same capability. If you are pouring outblack smoke, you may have a problem with the MAP sensor or MAT sensor, both of which are critical to speed-density.

[Dave M]

I'm pretty sure 3rd gen car do NOT default to speed density in the event of a MAF failure. There is no MAP sensor on a 3rd gen MAF car. If the MAf fails, you get extremely poor driveability, and stalling if the car runs at all. I know from experience

[KnightFire]

This was brought up on our SD forum:

http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/


HTH


KnightFire