90 CAS in a 92 GSX

[My1GLaser]

I am dropping the motor from my totaled 90 laser into a 92 GSX. I need to use the CAS from my 90, but the plug end on the sensor is different from the 92 wiring harness. How do I get it to connect? Should I hard wire it, and which wires splice together? Or is there some sort of adapter? Thanks for your help.

 

[Talesin]

Go to a junkyard and get the 92 Hall-effect CAS. It's MUCH better than the crappy '90 optical unit. Otherwise, when you cut off the plugs from the harness and '90 CAS to hardwire it, mail them to me so I can make myself a plug-and-play adapter. Doesn't work the other way around though.

Seriously, get the '92 black-top CAS. It's much better.

 

[My1GLaser]

Thanks for the idea! Is the plug end the same for the '92 harness and the hall-effect CAS? Because according to vfaq.com, the hall-effect is on the 93-94 and I don't know what type connector those years have. I just want to make sure it plugs directly in before I get one and find myself in the same position, but with a different CAS. Is it possible for this style CAS to smooth out small idle irregularities? My idle got MUCH better after I blocked the FIAV, but there were still some misses here and there. I have new plugs, wires, injectors, fuel filter, FPR, fuel pump, fuel lines. I was just blaming my stock coils since they are the original ones from 1990. But I have heard that the 1G CAS is inferior to the 2g setup and I guess that could have been part of the problem as well.

 

[steve]

The 91+ CAS have the connector on the sensor. The later black top hall effect sensor is a direct replacement with the 91+ wiring.

Ditch as much of the 90 sensors and wiring as you can. That also means loosing the 90 fuel rail and 90 throttle body.

 

[Talesin]

Eh? What's wrong with the '90 fuel rail and TB? Far as I knew, the fuel rails were the same across all the years. The 91+ TB is differently designed (especially the vacuum lines) but mine seems to be doing fine, even after 17 years on the road, no FIAV blockoff.

Er, and you don't have to lose the rail/TB to swap to the 93-94 Hall CAS if that was unclear. Check for vacuum and boost leaks to fix idle problems, and if you have an upgraded fuel pump, grab an AFPR and a gauge to get your fuel pressure back down to stock 36psi (no vac line). Should be idling around 20in/Hg (give or take 2) at sea level if you have an aftermarket boost/vac gauge hooked up already. Just spray some carb cleaner near the intake manifold juncture to the head. If the idle rises, you likely need to either get the nuts/bolts torqued down properly, or to replace the manifold gasket.

Guess this means I won't be seeing that plug in the mail any time soon. Ah well.

 

[steve]

Eh? What's wrong with the '90 fuel rail and TB? Far as I knew, the fuel rails were the same across all the years. The 91+ TB is differently designed (especially the vacuum lines) but mine seems to be doing fine, even after 17 years on the road, no FIAV blockoff.

Er, and you don't have to lose the rail/TB to swap to the 93-94 Hall CAS if that was unclear.

If your putting a 90 engine into a 91+ car you should ditch as much of the 90 sensors and wiring as you can. Since that means using a 91+ TPS and 91+ ISCy ou can't put them on a 90 TB, and the 91+ TB and TPS doesn't clear the 90 fuel rail. Therefore, that also means loosing the 90 fuel rail and 90 throttle body.

 

[My1GLaser]

DAMN! I did not know about the fuel rail. Freaking 90 model PITA. Steve, is there any way to mod the fuel rail to work? I guess I can find a used one, but it seems like every time I turn around another 90 part won't work. I already have the 92 TB & coil, and I know to switch ECU wires 6 & 14. I also have alot of sensors for the 92. You aren't talking about the O2, knock, coolant temp and oil pressure are you? (I just bought those 3 months ago before I totaled my Laser) Why do I need to ditch as much 90 sensors as possible? I just want to be educated about this rebuild I am doing. Boy did I get a handful here or what! But, at least I have an AWD w/4 bolt rear (no more one wheel wonder and quite a few upgrades came with the car!

 

[steve]

I thought there was a difference between the 90 and 91 O2 sensor but CAPS is on the old systems in the basement. The knock, ECT, and pressure gauges are fine. I assume you use the one good 90 part, the external oil cooler.

The factory ditched the unique 90 stuff for various reasons and there is value to following their lead plus they are the oldest parts used and had to find new since they were only used that one year. Using them is a long term problem for maintaining the car when you could use the more common parts and not hack up the wiring.

 

[My1GLaser]

Thanks Steve for the reply. Some of the wiring already has home made connectors, so I will already be addressing some wiring issues. Not many, but I have some good common connectors from the 90 to use. Yeah, I will keep the oil filter housing and my air to oil cooler! Like you said, most of the smaller sensors (ie coolant, rad. fan switch, oil) are the same. But that O2 sensor is different. (according to sparkplugs.com) Damnit. Oh well. I guess I will need the CAS and O2 sensor, but I will check the fitment of the fuel rail myself. (I weld and fabricate for a living, so I will see if I can make it work ok.) Looks like I have some more 90 parts to sell, so I will recoup some of the cost .
Oh, thanks Talesin for the help also, and idle fixes. I had 18 inhg when it was running, and boost leak tested to 20 psi just fine after I replaced the TB shaft seals and put a check valve b/w the PCV and the IM. I am running 43psi with my AFPR and it is accounted for in DSMlink. I was getting crappy hot starts, and read that vapor lock might be the prob and the fix was running a higher fuel press. Between that and the FIAV blockoff the car idles great comparatively. So, with the new coils and CAS it might be near perfect now. (Until I put in the 272s ) Thanks again for all the help guys!

 

[Cs4g63]

Go to a junkyard and get the 92 Hall-effect CAS. It's MUCH better than the crappy '90 optical unit. Otherwise, when you cut off the plugs from the harness and '90 CAS to hardwire it, mail them to me so I can make myself a plug-and-play adapter. Doesn't work the other way around though.

Seriously, get the '92 black-top CAS. It's much better.

What wires connect to what when you make the plug and play adapter? I already have the Hall-Effect CAS and the plug and about 6 inches of the wires, so I just need to know which wires connect to which wires.

 

[Talesin]

Haven't looked it up yet, as I don't have the wiring in question. :b Could probably email the guys at RRE and they'd have a better answer.

 

[Cs4g63]

Ah I will have to do that. I have had this stuff laying around for a while now and didnt even begin to think of doing it that way. I will have to do some emailing.
Thank you.

 

[Talesin]

Lemme know if you have a spare 91+ plug laying around, I have a (toasted) spare '90 CAS that'd be a perfect plug donor. And yeah, it was Robert over at RRE that brought the idea up, when it looked like my CAS was done for. Just make sure you leave plenty of slack wire, or get the lengths right, with allowances for adjustment.

Gonna have to raid a pick-a-part soon for a blacktop.

 

[Cs4g63]

Im at the local junkyards about 2 or 3 times a month looking for anything that I might find useful in the future. I will keep an eye out for an extra plug for you.