My 87GT 1227730 Conversion

[Fierofool]

Earlier this year I sent my 87GT out to Gabe Anderson for a 7730 conversion.  I’ve had everything for the swap, but just never got around to it when someone was available.  Gabe did the conversion and from what I understand, it fired up on the first try. 

I’ve been driving it for a few months and really enjoying it.  Took it on the RFTH 27 Scouting Run and got to play with some Porches on The Rattler but during that run, it developed a loud whine in the drivetrain.  Since the trans already had a faint whine, I guessed that was the issue.  Having previously bought another Getrag, I opted to just go ahead and have it swapped in.  New Luk clutch kit at the same time. 

When Scott dropped the drivetrain out, he found that the right drive axel had a ripped CV boot and all the lube was gone.  THAT was probably where the noise came from.  The axel was only about 14 months old.  So, in the process, a new axel was installed, too. 

Once everything was out, we found that the engine had been running so lean that the exhaust manifold had turned black from the heat and had cracked beyond compare.  The muffler that had a loose baffle had also blown a gaping hole in it.  So, a replacement exhaust system was secured from The Fiero Farm in St. Stephens, SC.  Just prior to turning the car over to Scott, I had upgraded the injectors because I found that the engine was running too lean.  However, I couldn’t see the damage it had caused.  There were other indications of a lean burn and when I researched the injectors, I found that the rebuilder had listed them as 17# when they were actually 14# injectors. 

Another consequence of the lean fuel mixture is that it welded the o2 sensor into the fitting on the crossover pipe.  Days and days of heating and soaking with penetrating oils were of little help.  Eventually, it came out, but it left half the threads from the sensor in the fitting.  Scott luckily had the exact tap (the largest he had) to clean out the threads for a new sensor. 

As the 7730 harness work was disconnected and pulled back through the firewall, we apparently pulled some wires loose.  That was a big issue for a bunch of us who knew nothing about repining, even though we had Sinister Performance’s pinouts.   

It took a lot of work to get things sorted out with Sinister Performance being very patient and helpful to answer the many questions I put to him.  Scott, Steve, Michael, Jay, and Roger all had a hand in sorting things out.  Even with the whole village fixing a Fiero, we missed some things.  A few days ago, we found a pair of wires that hadn’t been grounded.  It got rid of some trouble codes but may have caused some other codes to come about.  That’s yet to be determined. 

As the exhaust system was reinstalled, the crossover pipe changed positions and with everything back in place, we couldn’t get the coil pack and ICM to mount in their original location.  Scott devised a method to elevate it about 3 inches to clear the Digital EGR Solenoid and its mounting base.  It’s still in the same place, but just sitting a little higher. 

Some of the wiring looms had melted due to the extremely high heat in the engine bay that was caused by the lean burn.  The plastic wire loom melted to the wires and some wires were even damaged.  We got some High-Temperature Nylon wire loom from Pat, and Scott replaced the wires that were damaged or questionable.  Some things were rerouted just in case the newer wire loom wasn’t sufficient to protect the wiring circuits. 

This is a list of most of the things done to the car.

Clutch replaced
Transmission replaced
Cracked firewall side exhaust manifold discovered and replaced
Blown out muffler discovered and replaced
Torn CV boot discovered and axle replaced
Coil spring rubber isolators replaced
Electronic EGR valve wiring replaced and rerouted
Crank sensor wiring replaced and rerouted
Various wire looms replaced
A fusible link at the C500 had begun to melt.  Replaced
Spacers placed under coil pack
Connectors were placed in various ECM to allow for wiring harness removal
7730 conversion wiring mistakes corrected
Code 42 eliminated
AC high-pressure Schrader replaced
AC wiring corrected
AC low-pressure switch replaced
AC refrigerant leak corrected
AC recharged and functioning correctly
o2 sensor replaced

Might be another detail or two that were missed. 

Pictures of the project will be edited into the thread a few at a time. 

[scottb]

It was a buuuuunnnnnnnnccccchhhhhh of work. Jay came over and helped too.

Code 42 was eliminated, came back, and eliminated again. Not sure why the current O2 codes have popped up.

(I will admit that I was close to doing some 9mm troubleshooting)

Glad that it is all put back together and doing well

[Fierofool]

Original post edited to add Jay.  He's so quiet I forgot about him. 

[Fierofool]

This is a compilation of Gabes comversion and the work done by Scott during the transmission, clutch, and axel replacement. 

Top end off as Gabe started the conversion


Preparing one of the ECM harnesses


Repinning the ECM harness


ECM hooked up

[Fierofool]

After driving the car for several weeks and encountering issues during the RFTH scouting run, I decided a replacement transmission was in order.  At the same time, a new clutch was to be installed.  During the process, a torn CV boot was discovered, so an axle replacement was in order, too.

Drive-train dropped out.  While it was out, new rear spring rubber donuts were installed. 


Flywheel is in good condition


New Luk Clutch Kit in place


88 Getrag bolted up.  It got 2 new axle seals in the process


Torn boot and dry CV joint

[Fierofool]

Fixing things that came up during the transmission, clutch, and axle replacement.

While removing the drive-train, some wiring was dislodged from the new conversion and had to be repaired.

Heat damaged front manifold caused by injectors that were insufficient for the engine.


Replaced C500 fusible link that was starting to melt


The muffler had a loose baffle inside, but had also blown a hole in the side.  A replacement used exhaust was installed.


The battery tray was in poor condition.  It was cleaned, coated with rust converter and painted.  The vapor canister lines which pass underneath on 87 and 88 models were also cleaned and split nylon wire loom was installed over the lines to reduce further damage from battery acid. 


The low pressure switch on the AC compressor was broken and was replaced with the newer style 2-wire switch

[Fierofool]

Because of the high engine bay temperatures caused by the very lean condition created by the undersize (14#) injectors, much of the wire loom and even some of the wiring had heat damage. Some can be seen here.  New 17# injectors have been installed to overcome this condition.


When the front manifold and the exhaust was replaced, it caused a slight relocation of the crossover pipe.  For that reason, the coil-pack would no longer fit between the head and the EGR flange.  This worked well until exhaust work was done.  This photo shows the throttle body coolant lines in place.  They were eliminated to facilitate location of the coil-pac and ICM and to clean up the engine a little. 


In order to keep it in the same location, a modification was made to Gabe's original mount.  Spacers were added between the mounting plate and the coil-pack to raise it above the EGR flange.
Modification to raise coil-pack for clearance


Replacing the exhaust system.  While this was being done, the round cradle bushings visible here, were replaced with poly bushings. 


Drive-train back in place

[Fierofool]

I have continued to have a code 13 Oxygen Sensor and code 35 High Idle.  The oxygen sensor can cause a high idle, but it was replaced with a new Bosch unit.  It is being exchanged for a NTK sensor by recommendation of another club member. 

[Raydar]

I have continued to have a code 13 Oxygen Sensor and code 35 High Idle. 

When does the O2 sensor code show up? When the engine is cold? Or after it has been running for a short time, but is not hot.
When the engine is cold, the sensor should show ~450 mV on the scan tool. This is the default that the ECM is supposed to plug in, if it doesn't see activity from the sensor, while the car is still in "open loop". Once the car is up to temperature, the O2 sensor should start toggling between ~150 mV and 850 mV. Those two conditions - at least - are what causes "closed loop" operation.
The toggling part is working normally. The puzzling part is that the sensor shows a "cold" (or "default"?) voltage of 200 mV. This may (barring any other issues) cause the ECM to show a "lean" condition, and maybe set a code, and may cause it to dump in a lot of fuel. That's assuming it has gone into closed loop. It might also be what is causing your O2 sensor code.
 

[Fierofool]

I have already ordered the replacement NTK sensor you recommended.  This morning I went out about 7 while it was still cool and removed the Bosch sensor.  I found that the wiring connector wasn't fully latched.  I don't know if it was making full or intermittent contact, but the replacement sensor is on its way, now. 

The original EGR code came on while in closed loop.  I was on a long downhill coasting as I was approaching slowed interstate traffic.  I had 108 miles on it at that time, without any SES light.  Codes had been cleared prior to the trip.  At the end of the trip of about 130 miles, the Oxygen Sensor and High Idle codes were present.  The oxygen sensor can cause the high idle code I had been getting. 

I'll give it a test this weekend on the Sightseer's Scouting Trip. 

[Fierofool]

I replaced the o2 sensor and the common codes went away but the Code 42 came back.  It already had a new ICM in it and was working well until the o2 sensor was replaced on Tuesday evening.  Headed out on a 25 mile errand and the 42 popped up and the car will hardly run.  Have to rev it and floor it in each gear or it balks down.  I barely made it there and back.  It's now parked until time unknown. 

[TopNotch]

Want me to come over with my scanner?

[Fierofool]

You can if you want.  I have a meeting at 5 on Thursday.  The Code 42 says it''s a bad ICM but that doesn't seem to be the issue.  There is reference to voltage on terminal B4 that could be an issue. 

I'm up and moving around by 9.  Actually, I'm up way before that, but I usually don't get active til after 9. 

[Raydar]

Odd that it's still all this random intermittent stuff.
If nobody closer has one, I've got another 7730, if you want to try it. We'll have to plug your chip and knock module into it, though. 

The code 42 causes the car to run on base timing. Think of having the A&B pins shorted on your old ECM, except it's using whatever is programmed into the chip (probably ten degrees) since there is no distributor - and then trying to drive somewhere with it. It's no wonder it ran poorly. It had -0- additional timing advance. When we were testing the other day, I thought I saw 35 degrees at one point. That would be base timing (I'm guessing 10 degrees, as I said) plus another 25 degrees.
That's if I'm reading it right.

[Fierofool]

I don't know what kind of advance Pat was seeing today.  He did say that he also didn't see any knock counts.  He commented that he thought that if the knock sensor was bad or wasn't connected, that it could set a code 42.  He's asked to look at it so I'm taking it to him tomorrow.  I'll let him know that if he can't sort it out that he should call Scott.  He has 2 solutions available.