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A Proper Introduction

24K views 159 replies 24 participants last post by  nils302 
#1 · (Edited)
This started out as a more succinct blurb in my Garage Vehicle “History” block, but I figured I’d keep writing and turn this into a proper introduction post. I don’t imagine it would get much attention in the garage, and I think a lot of the community might appreciate the story and the pictures. If this is too long to read, then take a scroll through and check out the pictures.

My 1995 3000GT VR-4

(April 2018 picking up the GT in Erie, PA.)


1995 - 1st Owner: Doctor - Sarasota, FL
1998 - 2nd Owner: Tennis Pro - Clearwater, FL
2000 - 3rd Owner: My Father - Erie, PA
2018 - 4th Owner: Me - Jacksonville, FL

This history of this 1995 VR-4 is prefaced by its 1994 clone which was, unfortunately, sacrificed to the gods of stupid adolescent teens by yours truly (I wrecked my Dad’s first GT in 1999 when I was an irresponsible 17 year old):

My father owned a 1970 Ford Mustang Boss 302 for 27 years. He was the third owner (my uncle was the second owner). He kept the car in pristine shape while using it as his daily driver, except for winter. It demanded his attention pretty much every weekend, which he loved, but after almost 30 years he decided he wanted something modern, something that he didn’t have to work on all the time, but could tinker with when he wanted to. He sold the mustang in 1999 to someone in upstate NY I believe, and unfortunately we never really heard much about it since then.

(1985 my Dad and his Mustang)

(1990 Mustang engine rebuild #3)


He bought a pearl yellow ’94 VR-4 in 1999 from a dealer near Columbus, OH (I think it was Columbus). I wasn’t the biggest fan of the car initially. I didn’t know much about forced induction at the time, and was pretty put-off by the idea of trading the Boss 302’s thundering V-8 for puny, sideways-mounted six cylinder. I was rooting for Dad to buy one of the new Pontiac Firebird WS-6s with the quad-nostril ram air hoods! It didn’t take long though for me to come around all the cool technology (and outright wizardry for its time) that made the 3000GT such an awesome car. I went from a doubter to the platform’s biggest fan in less than the time it takes to drive from Columbus, OH back to Erie, PA.

As kids, my brother’s and I rarely got to drive the Mustang –high school prom night was the one exception where Dad allowed it, and believe me, you were being watched. But the 3000GT was a much easier car to manage, and he tended to be more trusting with it. So one Sunday night, after a lot of begging and pleading by me to let me take it out for a spin with my buddy, he reluctantly obliged. We had 40 minutes to be back, and strict instructions to keep it on the highway. He owned the car for a total of three weeks at this point.
 
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#148 ·
I believe my father found those when he was looking for a set of five-spoke '94 wheels to replace his six-spoke originals because they were flaking so bad. These were a pretty close match, and are still 18" instead of the 17" they offered in '94. I looked through his records, he got them in 2011 from partsgeek.com under part number ALY65744U85N. They don't show any hits now though for them under that number. He also got one wheel replaced after a bad pothole hit later that year from a site called wheelsandcaps.com under the same P/N. That site at least shows a listing for them still, but they're out of stock in all variants. Sorry.

And the 51 in a 45 was a favor by the cop. He had me clocked at 70. They do that a lot down here if you're nice to them and catch them in a good mood. I think that's as low as they can write them for, so that's there way of cutting you a break, but not quite as good as just giving you a warning. I think I can pay $50-$100 and take a four-hour class to avoid the rest of the fine and the point or two that it carries. But for $130, I'll pay it and be on my way.
 
#150 ·
Yeah I said that backwards. But what you described is what I meant. Poor control while operating at lower speed with the O2 sensors. It also has the hot-start stumbling issue too, and unfortunately I don't think they're related, so I have two big issues to try and resolve I think.
 
#151 ·
As to the hot start issue, you might just need to bypass/remove the fuel pressure control solenoid. Sometimes its operation isn't really compatible with a hotwired fuel pump and/or aftermarket AFPR. I removed mine like 10 years ago.

Read more here: Stealth 316 - Fuel Pressure Regulator Upgrade

"The fuel pressure control solenoid (or valve) is used by the engine control unit (ECU) only to increase fuel pressure during hot engine starts when there is a greater possibility of fuel vapor being generated in the fuel lines. When the air intake temperature exceeds 140ºF (60ºC) and the engine coolant temperature exceeds 194ºF (90ºC), the ECU uses the fuel pressure control solenoid (for up to two minutes) to allow outside air into the vacuum hoses to increase fuel pressure. In addition, the ECU increases fuel injector activation duration (richens the mixture). These two actions by the ECU are what I believe is a cause of the hot-engine hard-start condition I and many others have experienced on a hot summer day after turning the engine off for a short while. The engine acts like it is flooded for maybe a minute then runs fine. Because this is the only purpose of the fuel pressure control solenoid, I decided to remove it. I don't think there is much we can do about this part of the ECU programming short of going to stand-alone engine management. Owners that have removed the fuel pressure control solenoid, whether upgrading to an aftermarket FPR or not, have not reported problems related to this. I will update this web page if I encounter problems. If you decide to keep this solenoid, you need to modify the instructions that follow. "
 
#152 ·
Yeah, turns out it was O2 sensors this entire time.



I was delaying replacing them because I thought the downpipe had to come out to get the job done. Last time I had that pipe out I determined it wouldn't survive another remove and replace procedure without springing a leak in the flex section. Anyway, after looking it over and realizing the downpipe can stay put while replacing the sensors, I decided to go for it. I swapped out my old ones with a set of 3SX non-OEM units, and it fired right up!

Old front O2:


Old and new rear O2:


The maiden voyage went real smooth and all the drivability issues are gone. It idles smooth, transitions between closed/open loop perfect, and responds to high load at low RPMs without any hiccups.

Since the last update I've purchased Blackstealth's touch screen scan tool, which has been a huge help. In the interest of eliminating variables, I removed my Chrome ECU and reinstalled the original (repaired) factory unit. I also reinstalled my OEM MAF sensor in place of an Advance Auto unit I had tried a while back. With those back in, I was able to use the scan tool to verify O2s/fuel trims were reasonable, my TPS was on point and cycling to idle properly, my IAT was good, and all else was working fine.

Watching my boost, however, I was noticing I was only getting to about 6 psi. I triple checked all my vacuum lines for condition and proper routing, but didn't have any issues there. I leaked checked north of 30 psi and did not have any leaks. Finally got around to the wastegate solenoid, which is where I found my fault; it was stuck shut. It failed the resistance check across the terminals and jumping it resulted in no change in behavior. It's stuck in the closed position, so pressure or vacuum applied to the inlet port was unable to bleed. I tested both wastegate actuators directly with a hand pump, and they appeared to be operating per the book opening gradually from 5-11 psi. Instead of chasing down an OEM regulator, I'm going to use the opportunity to upgrade to Blackstealth's OLEDBC, and will replace the factory solenoid with a MAC valve.

Until that arrives, I'm enjoying riding around with the wastegates open to atmosphere. It’s a ton of fun with higher boost on tap; just sucks having to watch the boost and knock count like a hawk anytime I’m pushing it. Really looking forward to having the OLEDBC in place to keep things under control. I’ll keep the thread going as I get through that install and setup.


Temporary vacuum line setup to run the wastegate ports open to the atmosphere:

 
#153 · (Edited)
I'm wondering if the O2 sensor behavior in this clip is normal?

O2 Sensors After 5-hour Drive

I drove the car back from Atlanta, cruising at 80 and with a handful of short stops along the way. The car drove great. I had the scan tool running the whole trip to keep and eye on knock during accels. I noticed over time that low, med, and high trims all converged on 139%. Still the car ran well, even off the highway in stop and go traffic getting home. Once back in my garage and idleing I could see that the O2s were no longer cycling.

They woke up a little when I blipped the throttle, but still not exactly cycling. Does anyone know if this is normal? Maybe they're just heat-soaked from the long drive? Or should brand new sensors go right back to typical cycling when the engine is back in closed loop operation?
 
#154 ·
I installed an OLEDBC:

I decided to hide the box under the dash behind the existing ECU. I wanted to avoid cutting any factory wires, so I used some spade connectors to make a jumper tap to pull power for the unit from the cigarette lighter.





I grounded using a ring terminal to the console frame, and ran the wire along another harness in the center console.





I was able to repurpose the boost line and fuel pressure sensor wires I had ran previously to the dual gage pod, which I eliminated at the same time I installed the OLEDBC.



Moving under the hood, I fabricated a small square bracket to hold the MAC valve on the existing solenoid rack.









After removing the OEM wastegate solenoid, the MAC valve fit nicely in the same vicinity. I trimmed the vacuum lines to fit the new location.





Spliced the MAC leads into the provided harness using some crimp connectors and few different sizes of heat shrink tubing to make a weatherproof joint that could be tucked along the firewall.





Back in the cabin, I consolidated all the lines and bundled them together so everything could be tucked-away behind the console trim.





I installed the screen using Blackstealth’s steering column mount, which is just held in place with VHT tape. I’m not sure if I’m going to keep it here or try some other locations, so I didn’t go for any sort of permanent install just yet. Same with the selector knob, which I installed down by foot well/knee area. I think ultimately I’d like to come up with a solution to install the knob in the blank button location under the factory fog light switch.







I’ve been riding around with the controller for a few hundred miles now and it’s been great. I’ve got it dialed in to run the factory turbos around 14psi. It’s super convenient having all the features and ECU info available in real time.
 
#155 ·
A bit confused... Did you resolve the issue in post 153 ? previous post 152 you replaced the o2 sensors...

P
 
#156 ·
No I didn't figure anything out about the O2 sensor response mentioned in 153. The car is running night-and-day different (better) than it was from all the previous posts over the past few years, so I'm still confident the sensors had always been my drivability issue. I'm still not certain if what I show in the video is typical or correct however.

I've driven a few thousand miles now since replacing them, and based on my OLEDBC data it looks as if my low, medium, and high trim values have all flattened out at 139. Regardless of driving style, these do not appear to be adjusting at all. Again here, I don't know if this is correct, but the car is running great.
 
#157 · (Edited)
Hello,

In closed loop o2 voltages should cycle above and below ~0.45 - (Lambda=1.00). You would like to see low numbers then high numbers and so on. So depending on the update speed of the display and all at idle they change over slower 1/2-1 second or so. Possibly something has changed...fuel pressure, vacuum leak ?

Your video was real quick but it appears they did respond and show rich when you blipped the throttle quickly and they should then return to cycling. I didn't see you mention a wideband sensor....

I'm sure with all the work you have done you have reviewed Stealth 316 - 3S Fuel Trims

P

Edited for grammer and spelling
 
#158 · (Edited)
Yeah, everything I read suggests that I should expect a return to cycling behavior once it settles into idle, so I don't know what to make of this. Nor do I know if it's normal/typical for all the trims to lock exactly to the same value. I haven't thought about monkeying with the display refresh rate, maybe I'm missing some cycling due to that. I'll have to try that and see if there behavior changes.

Vacuum leaks are a no as I've replaced all the lines and leak checked north of 30 psi.

Fuel pressure is in check by a new AEM pressure regulator, which I've double checked for proper limits per the book.

I do not have a wideband installed. I'm pretty much completely stock except for the OLEDBC, AEM FPR, and an Evo IX BOV.
 
#159 ·
I didnt mean to imply changing the refresh rate. Meaning that a digital readout unlike a analouge X-Y plot only shows a static number when the sample was taken. Where you only see that number- .60 or .72 or .81 or what ever it may be at each sample point, so I think sometimes others have been thrown off when the dont see a 'certain' number that they expect instead of just observing that the numbers are cycling high/ low.

Have you tried having a friend drive while you observe and see if when accelerating they go rich ? or injected propane and look for that move to rich and fuel trim go negative?

In your picture post 154 it shows your fuel pressure at 21psi--- ?

P
 
#160 ·
Yeah I think the refresh rate possibly masking the response is also a long shot, but it is a valid point you bring up as this is intended to be part of the initial OLEDBC setup. I left the default value, but it would be worth trying to adjust more/less to see if the responsiveness of the sensors appears to change.

Yes they do show rich while accelerating, the strange behavior I see is that more-often-than-not, after the car is warmed up and I am in what should be a closed-loop operating area, I usually do not see the O2 values cycling.

The fuel pressure too has been corrected. That was an indication issue only by not calibrating my external fuel pressure sensor in the OLEDBC. There is a bias/offset you have to apply based on the specific sensor you hooking into the box. I attached a direct reading gage to the fuel rail, verified I was at 34 psi at idle, and set the offset in the OLEDBC configuration so my sensor display would match 34.

I'll get an updated driving video later on today to post that'll paint a better picture.
 
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