Superchip speed limiter question

[Tom Wilk]

But Troll, you're not nearly stock... But let us know anyway. I'd like to see how it does.

 

[Tom Wilk]

Oh yeah, Robert, how long ago did you live in the area? I drive that stretch of I-77 quite frequently. I've encountered some goofy drivers there as well, especially at 7 AM when I would be driving home from work (night shift) and catching the early rush hour. I was never in a good mood on those mornings. Our shift change has been moved to 6 AM and I tend to take the 2-lane roads more often now just to avoid conflict with stupid drivers. I'm irate when I don't get any sleep.

I hope you slowed down in Brecksville and Broadview Heights. They'll chase you down. Bro Hts still has their Mustang chase car and they love to hide.

 

[Tom Wilk]

Ok, I'm not really talking to myself here even though the last three posts are mine. Anyway, Robert peaked my interest in the motor. I had to do some poking around to see just how this variable intake system worked. To make a long story short, I couldn't find it.

Here's what I did find. I first took the plastic cover off the intake manifold assembly. The throttle assembly is right up front with the accelerator and cruise control cables attached to it. Then the manifold splits into two pipes, one going to the left manifold tube and one to the right tube. Right at the split is the EGR tube. From each tube, three runners drop down to the heads, the three from the left tube go to the right bank of cylinders, and the three from the right go to the left bank. Kind of looks like the cross-ram setup that GM used on firebirds.

Anyway, between the two manifold tubes is a solenoid valve with a smaller (about 7/8") pipe running to it from just on the engine side of the MAS in the air pipe. I first took the solenoid off and it is indeed an electrically controlled valve that when it opens allows flow from the small pipe to the intake manifold. I removed a seperate piece that the valve connects to from between the manifold tubes. Under that is a crossover that connects the two manifold tubes. There is no valve in the crossover, so they are always connected. The only thing this piece I removed did was allow the air from the 7/8" pipe to flow into both sides of the manifold.

I stuck my fingers into each manifold tube to see what might be in there (like a vacuum controlled throttle valve kind of thing). There was nothing there. I could feel the intake pipes on each side, as well as a couple of the runners that drop down to the heads.

I'm suspecting that this 7/8" pipe is just part of the emissions system. I don't think it's big enough to boost air flow enough to give a serious kick. What am I missing here? Is the SOHC engine different in later models?

 

[Robert]

Originally posted by Tom Wilk
Robert, yeah you do feel that thing open up. I was always under the impression that it was just getting into the power curve, but I've never really looked at the intake until today. It is quite a kick, and it does dust some vehicles when it opens up. It seems a bit more gradual when you start from a dead stop, but when you punch it up while under way, it is phenominal (sp?).

I wasn't sure if the 5 speed was out for your year. I'm aware of the use of the OD gear for the ratio between 1st and 2nd. I'm pretty happy with it myself. I'm even more happy with it now that I have the chip. It will kick down to the appropriate gear when you open the throttle and it scoots.

As far as tach readings, I've never seen it go over 6 grand. It just runs up short, which is why I figured 5800 RPM. I understand that the tolerance on these tachs isn't really precise so there could be some difference between what they read and what the actual RPM is. I know that the speedometer on mine isn't all that accurate. When I changed tires, the speedo became correct (as measured against Ryan Penner's GPS) while the odometer bacame about 5% slow as was expected. The speedo had previously been reading high. Cheap gauges, I guess.

I first learned about it by reading my Haynes manual. It says that the solenoid will remain closed until the engine RPM reaches 3,000. At 3,000 RPM it opens up to allow air through both tubes in the intake manifold. I tried using my scanner to find out exactly what RPM I am shifting at now, but it keeps loosing communications shortly after flooring it. I half expected that was what would happen since whenever I try and use the capture mode, it looses communications a couple of minutes after enabling it. If I sit in the driveway, it doesn't loose comunications so I was able to tell that my Explorer's tach reads 100 RPM more than my OBD-II scanner. My needle does go a significant distance past the 6,000 now. Before it used to shift as soon as the needle hit 6,000. I used my GPS when figuring out my speedometer accuracy. I found that mine was accurate until I put my larger tires on. After the tire change I read about 4-5 MPH too slow. Once I swapped my speedometer gear for one with another tooth (or was it one with one less tooth?) it now reads to within 1 MPH of my GPS.

 

[Robert]

Originally posted by Tom Wilk
Ok, I'm not really talking to myself here even though the last three posts are mine. Anyway, Robert peaked my interest in the motor. I had to do some poking around to see just how this variable intake system worked. To make a long story short, I couldn't find it.

Here's what I did find. I first took the plastic cover off the intake manifold assembly. The throttle assembly is right up front with the accelerator and cruise control cables attached to it. Then the manifold splits into two pipes, one going to the left manifold tube and one to the right tube. Right at the split is the EGR tube. From each tube, three runners drop down to the heads, the three from the left tube go to the right bank of cylinders, and the three from the right go to the left bank. Kind of looks like the cross-ram setup that GM used on firebirds.

Anyway, between the two manifold tubes is a solenoid valve with a smaller (about 7/8") pipe running to it from just on the engine side of the MAS in the air pipe. I first took the solenoid off and it is indeed an electrically controlled valve that when it opens allows flow from the small pipe to the intake manifold. I removed a seperate piece that the valve connects to from between the manifold tubes. Under that is a crossover that connects the two manifold tubes. There is no valve in the crossover, so they are always connected. The only thing this piece I removed did was allow the air from the 7/8" pipe to flow into both sides of the manifold.

I stuck my fingers into each manifold tube to see what might be in there (like a vacuum controlled throttle valve kind of thing). There was nothing there. I could feel the intake pipes on each side, as well as a couple of the runners that drop down to the heads.

I'm suspecting that this 7/8" pipe is just part of the emissions system. I don't think it's big enough to boost air flow enough to give a serious kick. What am I missing here? Is the SOHC engine different in later models?

The description of the VIS is "4.0L SOHC engines are equipped with a Variable Induction (VIS) System. The (VIS) system consists of an intake manifold tuning (IMT) valve mounted to the top of the air intake plenum and a vacuum control solenoid. When the engine reaches approximately 3,000 rpm, the PCM energizes the vacuum control solenoid which then controls the amount of manifold vacuum applied to the intake manifold tuning valve and the length of the time the valve is opened. As the IMT valve opens it allows both sides of the incoming intake air charge to blend together which increases high-end performance." It almost sounds like you were looking at the Idle Air Control Valve.

Dead Link Removed

 

[Robert]

Originally posted by Tom Wilk
Oh yeah, Robert, how long ago did you live in the area? I drive that stretch of I-77 quite frequently. I've encountered some goofy drivers there as well, especially at 7 AM when I would be driving home from work (night shift) and catching the early rush hour. I was never in a good mood on those mornings. Our shift change has been moved to 6 AM and I tend to take the 2-lane roads more often now just to avoid conflict with stupid drivers. I'm irate when I don't get any sleep.

I hope you slowed down in Brecksville and Broadview Heights. They'll chase you down. Bro Hts still has their Mustang chase car and they love to hide.

I lived in Toledo from August, 1992 through May, 1998. I was a Field Service Engineer. My territory stretched from Fort Wayne, IN to just south of Canton. I spent a lot of time back and forth along the turnpike, and down I 77. The company I was working for needed to cut 25% of its staff. Mine was one of the easier positions to cut since we had two Engineers in Cleveland that took over my Cleveland accounts, and 4 Engineers in Detroit that took over my Michigan, Toledo and Indiana accounts. The company placed me in Toledo when I started with higher expectations from our Sales staff. Toledo never really took off. I am originally from Arizona and the job prospects are much better here than they were in Toledo plus I had a 6 week old daughter so I didn't want to waste anytime looking in Toledo. I came back out to Arizona and got in with a company that manufacturers emissions flow measuring devices (E-Flow) among other things. The bulk of our E-Flow sales are in the Detroit area so I have been back to Detroit probably 15 times in the last 2 years. Each time I go back to Detroit, I go down to Toledo to see my old friends. Everytime I go back to Toledo, I realize how much I miss it which is why I have decided to start looking for a job that will get me back to Toledo. It should be a lot less stressful this time since I already have a job so I don't have to take what is offered. My wife's entire family lives in the Cleveland area and I still have a friend in Elyria so my Wife is totaly excited about the possibility of moving back.

 

[Tom Wilk]

that picture really tells the story, Robert, except that I don't have what it shows. The solenoid device I was tearing into was probably the IAC, judging from the way it looks. It's sitting in the middle right about where your VIS sits, but the VIS just isn't there. I'm wondering how its done now, as there isn't anything between there at all. Weird. It appears that both sides of mine are always tied together through the crossover.

I'm starting to wonder if it isn't just the way the engine is tuned that gets it to come on like that at 3000 or so. My Pinto ran like that after I put the cam in. It would just take off (sort of) when it hit about 3400 RPM and rev up quickly.

I'm also wondering if they tried a different approach, maybe a vacuum activated butterfly valve tied in with the throttle to not allow full throttle until the engine reached enough speed to pull in the charge. Kind of like the old quadrajet. I'm speculating here, but I'm at a loss as to how they might do this if they do it at all.

So you were a Toledoan, eh? That's not too far down the road from me. I'm living right next to Cleveland and I work down in Wadsworth, just southwest of Akron. I know what you mean by missing all the friends. I had a job offer in Las Vegas a couple of years ago, but I decided to stay put. It was ultimately the friends and family that kept me here. Having been out to Moab, however, I can say that the west is not a bad place to live either. I was in a fairly good position, I still had my job here (though when I first interviewed, I didn't know if I would be keeping it).

You'd certainly be welcome to the area if you decide to move this way. Let me know if you find something in Cleveland. I know my way around the western suburbs fairly well and can let you know what's decent as far as communities (though I imagine your wife is plenty familiar with the area as well). I don't know as much about Toledo, though I'm sure that you are familiar with it.

 

[flyguy]

I recently had my truck in at the dyno with my Jet chip in (which I was told removed my top speed limiter) However... my engine still cut off at 105. I asked the dyno guy and he told me that an aftermarket chip couldnt do anthing about the top speed limiter and could only mess with the rev limiter. Can anyone confirm this? I was thinking about getting my superchip soon, and was going to have it customed, and wanted to know if they could acually remove the top speed limiter... hmmm

nick

 

[Ru Dawg]

top speed

Well I'm not sure if the limiter is removed, but I have a Superchip and I've been up to 110mph so far and my engine was still going strong! Maybe someday I'll try to open 'er all the way! I don't get alot of chances 'cause there are not many roads safe enough to do it 'round here, live kinda close to the city and lots of winding roads.

 

[flyguy]

You said you had a SOHC though right? I dont know.. but I bet those have a higher set limiter than my OHV. Well... I need a superchip anyways... so one way to find out.

 

[Jornum1]

I have the sohc engine and it cuts off at 95 :-(
Also I still dont have my superchip. I spoke to chris from smartyparts and he said that there was a mix up in the shipping. He is sending me another one next day delivery. Hopefully I will get it tomorrow since he is using regular postal shipping. But I asked him about the limiter question and he said that with the 95+ explorers it should be moved to over 200 mph with the regular programing ;-) Not like I will ever go that fast, but I will be sure to try next week sometime. But he did confirm that mine at least will get bumped up.
I cant wait ;-)

 

[KeyserSoze]

ohv

I have the OHV engine in my 95 explorer and I have gotten it up to 105 mph. The explorer is stock except for a K&N drop-in air filter. I guess the OHV has a higher speed limit than the SOHC which seems strange.

 

[Tom Wilk]

I don't think that the top speed limiter is engine dependent. I think that it depends on the speed rating of the tires the car is equipped with from the factory. It is not the same thing as the rev limiter which is designed to protect the engine from over-revving.