Bringing a 88 Fiero Back to Life with a LFX Swap (Page 9/15)
MikesFirstFiero FEB 02, 11:45 AM
Glad to see another LFX conversion starting. Just a few considerations about using a 2013 drive train. I'm certain the earlier version of the engine electronics will be simpler to work with. It does not have the anti theft software that the 2018+ has. The engine will need a PCV modification to prevent clogging which is easy enough to do.

The transmission is first generation 6T70 and is known to be more fragile than the second gen starting in 2014. I looked up the MX0 tranny specs and see that it has a 2.44 final drive. Thats even lower than mine which is 2.77, your highway fuel economy will be outstanding. The manual shift operation on mine is all electronic with only two wires controlling it. It might be possible to change some parameters and add a simple switching cable with two resistors in it to make it work.

I've been fighting misfire at higher revs but now that is going away. It appears the primary cause is coking of the intake valves and GDI injectors that disrupts the fuel & air flow. All the GDI engines face this. My engine only has 60K miles on it and making it run right has been difficult. While I was able to run the Impala before pulling it apart I did not really ever get to run it to the redline where most of the misfire happens. I've done everything to avoid pulling the heads since it is in place in the Fiero. If I was starting over I would consider pulling the heads to have the valves cleaned and reseated and to remove the front cover to replace the timing chains. Those are known weak points of the engine.

But I didn't do that since it had no symptoms at mid revs and idle. So what to do? New plugs and coils made some difference. Then I did some hunting on the web and found a GDI intake valve cleaner product CRC GDI Intake Valve & Turbo Cleaner. Hard to find but not expensive at $16 per can. I got one a week ago and followed their instructions. It did make a definite improvement in the overall smoothness and high rev operation. They tell you to drive it every day after the treatment so that's what I'm doing now. After about 1K miles I'll do it again. I may also need to have the injectors cleaned by a local shop at $25 each but that will wait until I have the extra cash. If your engine has considerable mileage I'd make sure the intake valves & injectors are clean. I also have a catch can on the way to try to collect most of the blow-by from the PCV before it gets into the intake manifold. I will post when it arrives and I plumb it in.

[This message has been edited by MikesFirstFiero (edited 02-04-2022).]

Daryl M FEB 03, 11:45 PM

quote
Originally posted by Zefyr:

I have very much enjoyed watching your swap progress.

I have been planning to LFX/6T70 swap mine for a few years now, and it looks like I will be able to start on it this summer.

Getting the LFX cruise control to work is something I have been trying to figure out ahead of time, as with a few other things I anticipate being a challenge.

Keep up the good work.



When you figure out the cruise control, let me know. I started with the same Impala you are using. I went with a Saab F40 manual transmission. Bolts up easily to the LFX using the stock Saab clutch.
MikesFirstFiero FEB 04, 01:02 AM
My oil catch can came in today and was simple to mount to the engine bay next to the ECU. The one I bought was $35 from Amazon and came with hose (with fabric cording), fittings, clamps and a mounting bracket. It is a "Speedwow" brand (who names this crap?). I bought it from the Amazon warehouse since someone returned it, saved me $5. Well built, anodized and everything fit together well. Only issue is the top mounting hole on the bracket is behind the can body and it's difficult to get a nut in there. But five minutes of messing with it got the screw started.

I'm sure this will make a difference to reduce the coking of the intake valves. After getting the car running I pulled the throttle body off to do some work near the firewall. Before I began running the engine the intake was cleaned and dry inside and out. With only about 100 miles of driving the IM interior had a nice thin coating from oil mist. I've checked the oil level and it has not gone down at all, there are no leaks and the exhaust has no oil smoke. I'll keep an eye on the level of fluid in the can and report how things turn out.

The can installed

[This message has been edited by MikesFirstFiero (edited 02-04-2022).]

MikesFirstFiero FEB 22, 11:44 AM
I finally got around to looking at the steering shaft which is very loose. The free play at the wheel rim is almost an inch and this makes the car very difficult to drive at speed and on bumpy roads. Getting it out is simple, "just" crawl under the car and release the clamping bolt and "just" crawl into the foot well and loosen the other end and out it comes (if you can compress the slide coupling on the two halves).

Expecting the U-joints to be worn I ordered two new ones from Amazon, 1/2"DD to 3/4DD. They arrived and were nice quality stainless steel with no play at all. I expected the old ones on the shaft were the problem. Turns out the old ones were good. The primary cause was the sliding joint on the shaft uses nylon pads to allow the shaft to easily change length when installing it. That had compressed over time due to the forces of the manual steering. The second cause was the rubber vibration absorber allowed some movement too. Inspecting the bearings of the U-joints showed they were a bit sticky but still very tight. So the new U-joints went back to Amazon. A side note while these were nice units the end for connection to the steering column would not go on. The steering shaft DD has a bump on one side near the end so the shaft is polarized and can't be put on 180 out.

The solution was to lubricate the U-joints with Tri-Flow which freed them right up. If you don't know, Tri-Flow is similar to WD-40 but has banana oil and Teflon in it so it cuts old sticky grease and also lasts a long time. Then get out the welder and weld the slip joint and the U-Joint to the shaft end at the big end. Only problem is then the steering column needs to be loosened so the shaft can be reinserted sine it can't be compressed. Just more time under the dash and it popped right in. While under there I found my brake switch installation will need a mod too.

The brake switch is rotary and sits with the sensor at the limit when the pedal is not depressed. The ECU does not like that sometimes when starting since it thinks the pedal is not depressed enough and won't let the engine start. Only happens when there is no vacuum and the pedal is hard to press down. The body needs to be rotated a bit so the ECU is happy. That's a job for another day though.

The shaft after welding and painting



The slip joint that caused most of the problem. It won't move any more now.



The rubber isolator also fixed



After all that a test drive now shows I have only about 1/8" play which makes me very happy.

[This message has been edited by MikesFirstFiero (edited 02-22-2022).]

Daryl M FEB 22, 09:33 PM
That starting issue could be addressed by adding an electric vacuum pump to provide vacuum to the brakes under certain conditions my donor (2013 Impala) had this setup. To control the pump I used an adjustable vacuum operated switch and a relay.
pmbrunelle FEB 22, 10:56 PM

quote
Originally posted by MikesFirstFiero:
The primary cause was the sliding joint on the shaft uses nylon pads to allow the shaft to easily change length when installing it. That had compressed over time due to the forces of the manual steering.




quote
Originally posted by MikesFirstFiero:
The slip joint that caused most of the problem. It won't move any more now.



Yeah... the main reason for the telescoping action of that shaft isn't for installation. In case of a front-end crash, you don't want the impact to push the steering wheel into the driver. The telescopic section allows the steering rack to move backwards without ramming the steering wheel into the driver.

I would suggest starting over with another Fiero steering shaft.

If the plastic pads are destroyed on a replacement shaft, maybe you could restore it with polyurethane resin?

There are youtube how-to videos showing people pouring polyurethane to make stiffer engine/trans mounts. Maybe you could use a release agent on the DD shaft to make sure it slides on the polyurethane, with holes drilled into the female shaft so the polyurethane flows in and makes a positive lock.
MikesFirstFiero FEB 23, 09:13 AM
I have the Aux Vacuum Pump from the Impala and may install it in the future to provide vacuum on startup. But it's one more thing to go wrong. This only happens when I've been messing with the brakes and bleeding them. When the brake switch is adjusted I think the problem will go away.

As far as the steering shaft you are correct that this was done for safety purposes. I've looked for a NOS shaft but I've not found any so far. The original design is pure crap with the high forces of the manual steering causing constant wear on this part. The Impala shaft uses three rows of sliding ball bearings to do the job properly but it's way too short to be adapted. Maybe something else might fit in there.
Shho13 FEB 26, 10:47 AM

quote
Originally posted by MikesFirstFiero:


The slip joint that caused most of the problem. It won't move any more now.







THIS IS NOT SAFE, you NEED to get a new shaft ASAP. That is a slip joint designed to slide in on itself during a front end collision; with it now welded solid, the steering wheel will literally decapitate you in an accident.

Surely you can easily find one by posting in The Mall.

------------------
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MikesFirstFiero FEB 26, 02:05 PM
Well calm down a bit. I agree that it is not as safe being welded as if it could collapse. But it is only one aspect of safety for the vehicle since it also lacks ABS, Air Bags, Traction Control, TPMS and the last 30 years of crash protection design of the current crop of cars. In the bigger picture I expect that in a crash my low to the ground car will submarine below the newer taller cars and trucks of today and being impaled by the steering column is the least of my worries.

The idea that cars are "safe" or "unsafe" is a matter of degree not an absolute. I'm writing as an engineer with years of experience in equipment with life safety conderns. Driving a small, light car without modern safety equipment and with a 300HP engine swap is far from the safest choice of those available. In fact I'm still considering adding ABS from the impala if I can find a way of adding wheel speed sensors. Thanks for your concern.
Daryl M FEB 28, 12:13 AM

quote
Originally posted by MikesFirstFiero:

Well calm down a bit. I agree that it is not as safe being welded as if it could collapse. But it is only one aspect of safety for the vehicle since it also lacks ABS, Air Bags, Traction Control, TPMS and the last 30 years of crash protection design of the current crop of cars. In the bigger picture I expect that in a crash my low to the ground car will submarine below the newer taller cars and trucks of today and being impaled by the steering column is the least of my worries.

The idea that cars are "safe" or "unsafe" is a matter of degree not an absolute. I'm writing as an engineer with years of experience in equipment with life safety conderns. Driving a small, light car without modern safety equipment and with a 300HP engine swap is far from the safest choice of those available. In fact I'm still considering adding ABS from the impala if I can find a way of adding wheel speed sensors. Thanks for your concern.



I gotta agree with your assessment. Besides, many of the "government imposed safety items" are generic. By that I mean they are required for all cars regardless of design. Some cars had long steering columns that could impale a person. Others positioned the steering wheel so close to the dash that impalement was not even possible, but government rules are government rules. Not worth it for a manufacturer to argue the point. Cheaper just to comply with unnecessary rules.