Maniac's Dirty Unicorn '91 Isuzu Impulse RS Rallycross build

I've been working on an '87 Toyota MR2 for about a year now to prep for rallycross. I brought it from a shell that has sat for ages to a working vehicle which was just about to be tested in the crucible of motorsport. Then low and behold a guy named Hoser spots an ad from his old stomping grounds. He decides to post it to the 2016 Challenge Classifieds which then gets reposted on FaceBook. The combination of price at $1,500, awd, turbo, 90s goodness with a ton of spare parts, a rollbar, OMP race seat, multiple sets of rally wheels, and a trailer spurs me to work some things out with my finance department. This car was the 2006 National SCCA Rallycross Champion in Modified Awd class. Beating out many WRX and other AWD monsters with twice its power. The appeal was irrestible and I picked it up from Georgia on 7-16-16.

Now unfortunately after its run the car has sat. I haven't been able to determine exactly how long but I think its 5 or 6 years. So I tasked myself today with figuring out where its at and what it needs. I placed the car in its new home and set the battery on charge after a very long day of driving and manual labor pushing parts around that are designed to move under their own power.

Try this morning and of course flat battery so I grab some supplies. Oil, Brake Fluid, Fogging Spray and Sea Foam. I Fog the cylinders and gap the plugs while I'm at it. Plugs look fine so I won't worry about them too much. Oil checks out fine so I'll use it for now. I added seafoam and once I get it started I'll do an oil change after I let it get to temp. Radiator and overflow is empty possibly because it was in Tenn while it was sitting and PO was worried about coolant freezing. I add water and so far the system is leak free. The dash and gauge cluster had been removed for weight savings but I wanted the guages so I tried hooking it up. Unfortunately I seem to be missing some cables to plug into the back of the cluster. I'm not sure yet where they come from but there is several large plugs that are empty. I'll do some research to see if the gauge cluster is driven by these and if so how to get my hands on the harnesses.

So I gave up on trying to get the cluster and in and tried to start it. I got a small puff initially and then nothing. I can hear the relay clicking on and off but can't tell if the pump is doing anything. I added some new 93 octane and a bit of SeaFoam to the tank to see if it was too low. Still no dice. So I try some ether in the intake and immediately it runs until it has burned through the ether. So first thing to check is fuel pressure and there is basically none. I dropped the tank and pulled the fuel pump and was greeting with a rusty angry little thing that was really warm to the touch. I'm pretty sure I found my no start issue.

You'll notice in the last pic the pump is missing the sock. That appears to have disintigrated enough to have disappeared into the fuel tank. I'll be cleaning this thing out for sure it smells god awful.

On a positive note the cage looks great and the custom front skid plate is solid and the mounting system is very well done. It does weigh a ton though.

This will end my day, looks like I have a fuel pump to order, I already had a fuel filter on its way but the place the fuel filter is impossible to get at so that will be fun for near future me.

Watching...

pinchvalve wrote: Watching...

...with interest! Nice score. The car and trailer look good with some sunlight on them.

Vicariously stoked on this one... carry on.

So you'll be at Nationals this year with it?

hobiercr wrote:

pinchvalve wrote: Watching...

...with interest! Nice score. The car and trailer look good with some sunlight on them.

I know train wrecks are hard to look away from Watch as I put tons of stress on the specific parts that are really hard to find like anything in the rear suspension. I was really hoping to make it to the Firm rallycross on the 23rd with it but I don't see that happening unless I magically get the fuel pump in record time from Rockauto, find an evening to put it in, and there is literally nothing else wrong with the car. Still it's nice to be able to use the trailer to take my MR2 to the event in case something goes wrong with it.

Interesting.....I didn't even remember that these were AWD. $1500 for all that AND the trailer? killer deal...

irish44j wrote: Interesting.....I didn't even remember that these were AWD. $1500 for all that AND the trailer? killer deal...

I temporarily forgot it was AWD as well when I punched myself in the face trying to undo the driveshaft bolts to drop the tank and one of the wrenches slipped. Might have been more of a concussion situation than a lapse in automotive knowledge.

irish44j wrote: Interesting.....I didn't even remember that these were AWD. $1500 for all that AND the trailer? killer deal...

And the AWD is a 30/70 F/R torque split.

NickD wrote:

irish44j wrote: Interesting.....I didn't even remember that these were AWD. $1500 for all that AND the trailer? killer deal...

And the AWD is a 30/70 F/R torque split.

Anyone got any literature or pics of that setup? that is really really odd from a transverse engine car.

MrJoshua wrote:

NickD wrote:

irish44j wrote: Interesting.....I didn't even remember that these were AWD. $1500 for all that AND the trailer? killer deal...

And the AWD is a 30/70 F/R torque split.

Anyone got any literature or pics of that setup? that is really really odd from a transverse engine car.

I don't think its really 30/70 the only place I have seen that is the ad by the previous owner. It does have a welded rear diff so maybe that has an affect on the split but I don't think it would work that way. Most places I've read show a 43/57 split and auto-catalog.com shows a 50/50 split.

Got a couple minutes of free time today so I pulled all the wires and connecting hoses needed to get the fuel tank all the way out. I drained the tank of the old nasty gas to see what I'm working with. The exterior is filthy from its life on the dirt but the interior is surprisingly nice. I see no rust, just a small amount of black gritty stuff in the bottom.

I decided to clean out the inside since I had the tank down anyway and I'm waiting for the fuel pump to arrive. I use a mix of water and vinegar and let it soak. I use this mix because I can easily drain it w/out worrying about poisoning my local neighborhood. I started to clean off the exterior so its not so nasty when I reinstall. I'll also rust reform and paint any rust spots on the exterior.

After it soaks for a day I will dump about 1/2 of it out and add a couple thousand bbs to the tank. I slosh those back and forth until my arms and back give out and then I drain everything taking care to get all of the bbs. The fuel pump is set to arrive tomorrow so we may be blessed with a first start video if I can find the time to install it. I'm crossing my fingers.

Found a couple more minutes after the kids went to bed to take care of a pet peeve of mine that demon known as rust. Theres nothing I've found rusted through or anything but the bar that goes across the interior under what used to be the dash pad was rusty.

I took it off and started to grind away the rust. I use a metal wire wheel attached to my cordless drill for most of the work.

Then I hit it up with some rust reformer to take care of any missed spots and to make sure I don't see the nasty stuff return.

While waiting for the reformer to dry I went through my box of extra parts. I came across a big box of nope.

I sprayed it with the reformer as that was the only thing I had on hand. I'm not sure if it will kill it or just keep it from oxidizing. After the reformer dried I hit the piece up with some gloss enamel black paint and will let it dry overnight.

Well, not much worse than an oxidized spider.

Otherwise I'm just jealous as hell, Looks like a kick ass project start.

So the thrash continues pushing hard to get to the event 3 days from now on Saturday. I got the new fuel pump installed the little rubber piece at the bottom of the pump is almost useless as its really mushy and sticky. I'll probably regret using it but I didn't have much choice at the time. Got all the various hoses, wires and whatnots hooked up and reinstalled the tank. I'm sorry I dont have many pics I'm so pressed for time between job, kids, house selling that I'm moving as quickly as I can not even pausing to snap pics. I jump the pins for the pump and it sounds strong and I can hear gas moving around from the back to the front to the back again, good sign. Start the car and it sputters to life barely running and won't rev.

I had a fuel filter on order at Autozone so I picked that up. I then managed to nearly round the nuts on the fuel line and not accomplish anything. I decide to leave it be before I break the line and move on to something the previous owner kept on mentioning and a common issue with this engine. The CAS crank angle sensor. It's a little hall sensor mounted below a wheel that is where a distributor would normally be in the NA version of the engine. Its known to have the soldering inside come apart and there are instructions online to fix it. I dig into the system and get the little bugger out including one very small and very hard to reach bolt. As I'm removing it I realize that I never had to unplug it. I search around an lo and behold theres the plug hanging down. I decide at this point not to try to do the fix as that may have not been the problem and you can potentially destroy it trying to re-solder the pins. So I pop in the car and that takes me to this video, it gets really interesting starting around a minute 30:

Impulse 2nd Start

That's awesome.

Nothing sounds better than a car starting after a long sleep.

That is mega cool.

So I've still been busy on it. I'm not giving up on the rallycross tomorrow atleast not yet. I took the car for a drive yesterday to see how it behaved. The good news is most things seem to function correctly. Brakes, gearbox, clutch, steering all seem decent. It feels a little odd almost crunchy when turning but that may be the rally tires and the welded diff along with never having owned an AWD car before. The long and the short of it is its gutless and bucks like a madman at full throttle. So that hesitation I was feeling sitting still equates to near undrivability. I purchased and installed new plugs and that helped but its still not right enough to race. I thought perhaps it was low on fuel as I completely drained the tank to clean it so I put a bottle of regane in it and another 2-3 gallons of 93. Still no change.

At this point I revisited the CAS as the bucking wildman part is one of the major symptoms. I followed the instructions I found online from a lotus guy and carefully peeled away the rubber. I then cleaned the circuits with a wire hair brush until I could reasonably re solder the pins.

I got that squared away and used some orange sensor safe gasket maker to replace the rubber I cut away.

I reinstalled the sensor and the car felt the same as before.

At this time I revisited the fuel filter. I made a hash of it completely rounding off the fitting going into the filter. I knew I would have to cut and fix the fuel line with a new fitting. So I started looking online to learn how that is done. I cut the fuel line and installed a new compression fitting on it.

I attached the filter and hooked up the other side which thankfully I hadnt ruined while removing.

Put everything back together and... no difference. So now I'm wondering if I soldered the CAS right or if something else is wrong with the car. I'll have access to a code scanner this afternoon so I'm going to pull the codes and see what that shows.

Hate to be the guy who just throws parts at it but these are my two guesses from dealing with older cars that have sat:

MAS/MAFT/MAF. Anyway to check voltage and continuity?

ECU: could have leaky capacitors.

I've failed, I replaced the fuel filter still no change. I removed the CAS and undid all the goop again and then checked it for continuity and it passed just fine the solder is fine. I pulled the maf and cleaned it with contact cleaner, checked timing, pulled the cam position wheel and made sure it was installed properly. No change. The car idles fine, It revs to redline with only a slight hesitation at the low end but when I try to drive it I have no power at all and the car keeps on trying to cut out. Looks like I'm going to need to dig deeper than I have time for before tomorrows event.

Fuel pressure regulator? Hate that you didn't make it to the rally cross, but still looking forward to seeing how it goes! Rivergate Racing did the roll bar & skid plate, and they do amazing work. They did 2 of my race cars.

So I've been pretty busy lately I'm in the middle of selling the current house and buying a new one but I've been able to sneak in some time here and there. I've tested the MAP sensor and fixed the vacuum hose going to it to make sure it was leak free. I've replaced the Coil Packs and I cleaned up the ground wire to the battery. This got the car in much better shape its actually drivable as long as I keep the rpms and throttle down. Now I have some sort of fuel cut that is happening. It seems to be related to boost but is also a common symptom of the CAS. The oil return from the turbo is leaking pretty badly so I figure I'll repair that and check out the wastegate while I'm at it.

I quickly determined that I would need to pull the radiator to have the access I want to the turbo so I pulled it out and flushed it with hose water to clear out any gunk. Now I can see the hair dryer in all its glory.

Not very large but its only a 1.6l anyway. I'm tempted while I have the whole thing apart to install the volvo intercooler that I was given with the car. It is a nice upgrade but I think I should get everything running properly at stock levels before I add in the complication of modding to the diagnosing process. Here's the part that is allowing all the oils to escape and turn into a smoky mess on the down pipe.

It had some white goop as a gasket as well as some sort of gasket and it was leaking pretty good. I'll probably have to make my own gasket as it seems to be nla through the usual sources. I'll try taking it to Napa first and see if they have anything that's the right size. The other end goes to a rubber hose that was replaced at some point. It seems to be a touch too large and it should have a 90 degree bend. This one was a straight hose that was bent and that put a large kink in the hose.

The shaft in the turbo seems to be good doesn't have a lot of play in it and there isn't any oil in the outlet to the intercooler so seals seem to be in good shape as well. While I've got everything torn apart is there anything else I should check while I'm in. I'm doing inspection and repair of any split vacuum lines that I see.

Went to the parts store and got a nice shiny hose for the turbo drain. Ended up using some sort of transmission hose because they didn't have anything for oil apart from straight hose. I figure it will hold up just find with some frothy hot oil pouring down it. At least its not under any pressure. I also replaced the wastegate with a spare I had for the car. I didn't have a good way to test them so I went by feel and condition and picked the one that I thought was in better shape.

After putting it all back together I filled up the oil and coolant and turned the engine on. The car would idle but would die as soon as I hit the gas. So I shut it down again and went over some of the other vacuum lines I saw, replacing 2 more with some spares that weren't cracked. Started the car up and it would now rev properly but then it started acting strange again stuttering and feeling like it was bouncing off a very low rpm limiter. I shut the car off thinking it might be in a limp mode and restarted it. This time it felt great revving straight to redline with no hesitation. I backed the car off the ramps and let it idle for a bit. It started smoking a ton from the exhaust and from around the exhaust side of the turbo housing. I took the car for a spin and it felt better than it has before but still is hitting a fuel cut or limitation or something.

I have a harness on its way that will allow me to hook the gauge cluster back up so I can check codes and along with that is a new CAS sensor. I will have to wait for these to come in before I continue troubleshooting. Hopefully I see it arrive early this next week so I can install the CAS. I'm trying to make it to a Rallycross event on the 27th at Port St. Lucie. For the oil leak it may be a stuck pcv pressurizing the oil pan or perhaps I just put too much oil in it. Hopefully nothing major like shaft seals.