Motor swap
 

I am swapping motors in an 86 iroc Z camaro which is a 5.0. The new motor is a 5.7 liter out of a 1989 formula firebird. I am removing all the smog and catalytic converter off tje 86. Does any one have some tips on getting this motor to run in the 86 after plugging all wires together. How to bypass the stock smog components?

Surely this is a carb'd 'engine' correct? It should run anyway.

The '89 is a TPI engine, but you don't say what the '86 is. As there are a number of changes, even if the '86 is a TPI car, the BEST way would be to take the computer harness with the engine.

Without a schematic in front of me, I don't know how 'dangerous' it would be to just swap computers without the harness, IF they are both TPI.

Good point, and what about the trans?

The Geek is correct, the '89 is a tuned port injection engine(even injectors fire at the same time, odd fire at the same time).......

You will have to swap out the ECM's and harness......

As for no cat, this is OBD I, so the system doesn't even know if there is a cat there......the only other smog device might be an air diverter valve....what other smog components are you talking about?

I think it has one oxygen sensor ahead of the cat . I can't remember if these came with true dual exhaust. If so then two oxygen sensors. Since you are removing the smog equipment, these would likely be removed as well. If the computer doesn't see it/them, it will illuminate the check-engine light. If the bulb isn't in the socket for the check-engine light then you'll probably not notice a difference except: if it has an automatic transmission, I believe it will not ever engage the torque-converter clutch while it thinks the check-engine light is on.

OBD II had an O2 sensor after the cat, to test it's efficiency, OBD I didn't.....so not having a cat would not be noticed on an OBD I vehicle, by the ECM/PCM....

I thought that only occurred if the PCM detected misfires?

You can have misfires in fourth gear with TCC applied on an OBD I or OBD II vehicle...

Storytime with CathedralCub:

When I was younger I bought a mid-80's LeSabre with an Olds 307. State law where I lived required that it had to pass smog in order to be sold to me. I drove it around probably 40,000 miles before the 2-year re-inspection was due and it never missed a beat.

I went in for the test and came through with good emissions, good gas cap, etc. and failed for no Check Engine Light with ignition on and engine not started.

At this time I didn't know the computer's interactions nor the smog laws surrounding them very well so I never once thought about no self-test of the CEL. My previous car was from the early `70s so I never had to worry about it.

So, I pull the dash apart to check for a bad bulb. Sure enough, it had exploded. I replaced it and voila': CEL is on all the time.

Yay.

So then, pre-Internet, I dig around in manuals, ancient scrolls, and stone tablets to figure out if there's a way to diagnose it. I found out about the flash codes. Being a computer guy (that happened to be raised by a mechanic) I was excited to discover that for only ~$60.00 I could buy a plug that makes the computer flash me the codes and a book to tell me what the codes mean. It didn't take long to discover that the plug was just glorified molded marketing success that took the place of a paperclip. But still, I had the book in paperback so that was okay.

The code was for the MAP sensor (if I recall correctly). I replaced it and went for a drive.

This car has a Hydramatic 250C Metric transmission, so 3-speed with a converter clutch. It also has a 2.41:1 rear end and I upgraded from 205/75R15 to 235/75R15 tires right after I bought it. This car has looong legs. At WOT it naturally shifts out of 1st at over 50MPH at 4,000RPM, and 2nd at about 90MPH, also at 4,000RPM. How do I know this with an 85MPH speedometer? Well, the needle points where it wishes 90MPH was stenciled, and also because I installed a tach and did the math.

One thing I didn't like about the car was that it had ~30% less engine and weighed a good 1,500 pounds less than the previous car, but only got about 1MPG better no matter how nice I was to it. I chalked it up to emissions equipment strangling the engine.

So back to the question at hand: I had driven the car quite a bit at this point, and knew its behavior pretty well. After replacing the MAP sensor I went for a drive. Just normally accelerating it goes first, second, third, fourth . . . wait, what the h3ll?

Slow down then speed up and it does it again!

Then I realized: It had never engaged the TCC before while I owned it. Not ever. I had always thought I just wasn't able to notice it or it happened at a higher speed to be less perceptible or something. Being geared so tall it was definitely noticeable when you touch 35MPH (indicated) and the engine drops ~300RPM .

I tested my theory on my parents' early-`80's B-body also with a 250C (that we thought for a long time was a 200-4R) and sure enough, I could make the CEL take the place of a working TCC at will.

And bonus: My LeSabre consistently got 17MPG or better from then on, often getting a bit over 20MPG on long highway trips if traffic (and my foot) was light.

This also meant that it was likely the sales lot I bought the car from had a buddy with a smog shop that rubber-stamped the emissions test when I bought the car. Could have been much worse I guess.

Over the next few years I often had occasion to tinker with friends' and girlfriends' and colleagues' cars. I noticed that on probably half of the '80s and early `90s GM's that I put my hands on, if the CEL was on they often were not engaging the TCC. Sometimes this was how they were when I found them and a friend etc. didn't have bazillions to pay to get the car to pass smog. A couple of times I provoked the issue by finding a MAP sensor and disconnecting it to see what happens.

My `97 LeSabre does it whenever the 180-degree thermostat doesn't let the engine get warm enough on really cold days. CEL will come on and it never engages the TCC. Reset codes, even while driving, and the TCC is back. Code is for low engine temperature. I went back to a 195-degree unit a few months ago and now my fuel economy has gone back up and we'll see how it does this winter.

Wow, I type like a Northstar too I guess. I'll go add "Storytime with CathedralCub" up at the top before clicking [Submit Reply]