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

Looks like I'm missing another event. I finally did something I probably should have done a bit ago I pulled the injectors. This was prompted by a Isuzone member reminding me that I can pull the valve cover to have easy access to the injectors. Well.... easy probably isn't the right word but at least I had access.

I did get a chance to look at the top of the head as well and it looks decent no sludge buildup and some normal bronzing for a 25 year old car. The previous owners believed in general maintenance, I'm fairly certain the car has been adult owned for its life up until now that is. Now its just owned by a kid who's well past his shelf life.

Following some advice from a couple GRMers I rigged up a redneck injector cleaning setup. I used a 9v battery connected to an old injector connector from my MR2 I had lying around. This opens up the injector allowing me to spray compressed air and carb cleaner through it. Start from the engine side blowing backwards up thru and then follow up going the other direction.

Using this method I got two injectors flowing pretty nicely with a good spray pattern. Unfortunately I also have 2 more that are completely clogged and any attempt to blow cleaner through them just popped the hoses off. They also sound a lot more muted when opening and closing. I eventually got something like a trickle through them going back and forth. I'll soak them for a couple days in the cleaner and see if that will open them up any.

Between cleaning these and the new CAS thats coming I'm pretty confident I'll have it running right really soon. Unfortunately I don't it will be soon enough for the August 27th Rallycross. : (

The adventure continues... I started to take the injectors out of my spare engine and got a nice surprise the head on the spare is incredibly clean. I wonder if it was rebuilt or in the process of. I know nothing about this engine how many miles are on it or anything. I was planning on tearing it down and rebuilding it as my phase 2 high compression turbo engine but that may change if I find it was fully rebuilt.

Either way I pull the injectors from it and test them out. Just like my other engine I have 2 that flow pretty nicely and 2 that seem gunked up. My testing method isn't exactly sophisticated but I do the best I can with what I gots. Either way I set the two gunked up ones aside and match the good ones with the good pair in the car. I eventually get it all back together which surprisingly wasn't that big of a pain.

Throw everything back on and start it up. It sounds good and I take it for a spin. It still has a hesitation but is no longer hitting a boost cut situation. I had received a box of goodies I bought from another Impulse enthusiast and that box included a new CAS. So I pop that on no real change in performance. Included in the box was the wiring to hook up the gauge cluster so I plug everything in and surprisingly it all seems to be working well. Except oil pressure which I had noticed a broken plug that is the likely cause. Most importantly I have the check engine light available. I only get code 12 which is a check of the diagnostics so I decided to unplug the map and see if I can force a code. That gives me the expected code 34 for a map but interestingly the car seemed to run better with it unplugged. This points to a bad MAP even though it tested out ok. I'll order a new one since they are cheap and try it out.

Currently the engine hesitates slightly to heavily when accelerating or revving in neutral. To have the engine run best I need to have the CAS set all the way to one direction. If I adjust the CAS the other way the car will shut off while idling. This points to a timing issue as well as a possible map issue from above. Anything else I should look into? I know that valve timing is correct and the CAS can only be installed one way.

I was thinking about your Impulse tonight and it made me spend way too much time on CL.

Spending time on Craigslist is always fun. Give yourself a fake budget and some criteria and goto town. If you want to go crazy look on searchtempest so you can easily scan the nation. I'm smack dab in the middle of settling into my new house and my garage is half full of boxes. Updates will come along once I get my garage back in order and get back to wrenching on the Impulse.

Incoming big update. I moved and that put everything behind but this month I made it my goal to get my garage in order, get the car in the garage and start figuring out whats going on. She's so pretty in her new home:

To recap I got her running but while she idles fairly smooth she won't rev properly and under load is completely gutless. This week I replaced Fuel Pressure Regulator, MAP, CAS, O2 Sensor, TPS, IAC, and took of the timing belt to check mechanical timing. Finally my buddy Timmy came over and we compression tested the car. We found the #3 and #4 cylinders to be low, nothing to it but to pull the head.

Yup bad head gastket was allowing compression to pressurize the crank case which also is the likely culprit of the oil leaking from the turbo center section.

The car came with an extra engine and the head looked real nice on it so I decided I will use the head from that engine.

I decided that while I have the head off I'm going to clean up some of the extra stuff in the engine bay that's no longer needed like the heater hoses and cut off A/C lines.

I also started digging into the remainder of the HVAC that was in the car and found that something had at one point called it home.

So I ripped it all out and a bunch of sound deadening that was behind it.

Getting a little frisky with the paint cans while I have everything apart. Kinda silly to do on an inexpensive rallycross car. I chose those colors because I had the paint for it but also because I like the Lotus '79 and Lotus designed the suspension on the Impulse so you know connections and things but mostly because the previous owners of my new house left the gold paint here.

Glad to see you back at it. Amazing what we call 'fun' sometimes. But at the same time I'm really diggin this one. Keeps me motivated in case I find an equally bonkers project to dive into.

-Hans

Isuzute Impulse RS

While I've had the idea to pull the hatch off since I got the car last June the name is a blatant rip off of the recent Mighty Car Mod / Roadkill episode.

Think the weight loss is going to offset the aerodynamic drag it's inducing?

I don't think either factor of the 60 lbs it weighs or the drag really matters in SCCA Rallycross. The biggest bonus and the reason I actually took it off was to clean the inside of the car. In fact I was just gonna post some before/after pics from a nice round of pressure washing.

Before:

After:

Super mega bonus. While cleaning up the head I'm planning on using I discovered the head has had a fair amount of work done to it. I can't see the intake ports but I can see the exhaust and they have definitely been worked over.

Stock Head:

Ported?:

The bowls have been worked as well. But it looks like it has some damage on the number 2 cylinder. I'm thinking the previous owner of this engine ran a bit high in the boost and a bit low in the fuel. The actual block looks fine and the number 2 piston seems fine as well. What do you think? My mechanic buddy says its fine to use, anyone disagree?

Prep work on the head and chassis continues while I wait for the gasket set to come in. I cleaned up the head/intake/exhaust manifolds with a bit of degreaser, scrubbing, and pressure washing.

I added a bit of black paint to the DOHC 16V on the intake manifold to make it pop a bit. After the cleaning I sprayed the cams and valves with fogging solution and spun the cams to work it in a bit. The valve springs are definitely stiffer and "snappier" than the other head.

I'm also experimenting with filling in the motor mounts. In the past I've used the 3M window weld which works fine but its $20+ a tube. I found some Urethane at Home Depot at $4 a tube. So far it seems like it will work well. It is stiffer than the Window Weld though so I assume that will translate to greater vibration.

Another weekend another round of busted knuckles. Not really today was a fairly light day of prepping the head. Because I'm using the head from the other engine I had to transfer some of the sensors over. I got the temp, iac, tps transferred to the new head.

Because I removed the heater core and the coolant to the throttle body I had to figure out a method of looping the heater hoses back to the system. The whole goal of this was to reduce the crap under the hood so I didn't want to just loop it at the firewall. Instead I used some of the unused heater pipe and some 90 degree hose to create a new section and made a bracket to secure it to the thermostat housing.

I also am removing the EGR and so I blocked the exhaust and intake sections of the EGR. For the intake side I just created a little plate and bolted it on. I only have an air powered cutoff wheel and my bench grinder so fab work is fairly basic but I'm happy enough with how it turned out.

For the exhaust the old bolts broke and were too short to use as studs so I couldn't make a plate. I was going to tap the hole and just thread a bolt in but the hole is bigger than my largest tap. I decided to try JB welding in a bolt. We'll see if that holds if not I'll buy a tap and bolt large enough or get the old broke bolts out and create a cutoff plate like the intake one.

This week during the week I'll transfer the fuel rail and injectors and fill the other motor mount then next weekend I hope to have it all put back together.

Really glad to see this coming back. I love the work you're doing.

To plug the exhaust side you can use a pipe tap and a pipe plug.

In reply to f6sk:

Yeah that will be plan B when the JB weld inevitably fails. Hopefully it will spit the bolt out at speed and let it bounce around under the hood. Everyone needs some cool stories to tell their grandkids.

Threw a bunch of hours at the car today but didnt get as much done as I would like. Its crazy how much time the little details eat up. I started with the fuel rail and injectors. Got that all squared away and attached the wiring harness where I could. I also did some cleanup on the harness putting in some new loom and re-taping the bulk of it.

I hung the head on my engine hoist and promptly broke the vacuum solenoid that opens the intake runners I had been trying so hard to keep that stuff in good shape only to bonehead it at the last second. I decided I'll bodge the runners open and maybe worry about it later. Hopefully I'll be high rpm, high load for the bulk of the cars time running and it won't make a difference.

I dangled the head a couple inches from the block and started reattaching items I hung the exhaust manifold. I then lined up and dropped the head down onto the block but didn't tighten the head bolts and got all the oil and coolant lines for the turbo hooked up. I then swung around to the other side and connected the knock sensor, oil pressure, and fuel inlet and return line. Finally I tightened the head bolts as show in the big green book.

I then placed the painted valve cover on for some sweet photos.

Welp now she's a runner again. Got most of it back together and did a test start to make sure I wouldn't have to pull it all back apart again. First start after Head Gasket Replacement

Great News!!! I got it running pretty decently. The fuel pump came with an incorrectly sized O-ring and it wouldn't provide enough pressure. I changed the O-ring and voila it runs pretty well. At least enough to drive down the street and hit 40mph. It has a problem where the car shuts off while coasting to say a stop sign but it will idle in my driveway. I also had a bad leak at the turbo seals so I swapped in the spare turbo and fixed that. Unfortunately I created another leak while I was at it. It only happens while running so I think its the return line on the spare turbo.

Unfortunately I decided to sell the car. I had been thinking about it for awhile. My daughter is more attached to my old MR2 she never took the Impulse very much. I also have a lot of new parts on my MR2 including nearly all the braking and suspension as well as rebuilt engine/clutch tons of stuff. I can do the same on the Impulse and it really wouldn't be that expensive but I've been wrenching on cars for 2 years without hitting a single event. I want to take the path of least resistance to hitting the dirt now. For Sale Thread

This thing is so cool. I'm sorry to see you sell it, but hopefully it makes an appearance at the challenge or at least at a rallycross soon!

cmcgregor wrote: This thing is so cool. I'm sorry to see you sell it, but hopefully it makes an appearance at the challenge or at least at a rallycross soon!

Yeah there's a bit of sadness for me as well. Especially since I had met the previous owner and his love for the car and the success it brought him. I will be going back to working on my MR2 which I have a lot of love for as well. I will take pains to make sure the Impulse finds a good home and it's close enough to driving properly keep someone motivated.