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So bought dave's 87 iroc with the legendary SLP T-ram. If you've researched these intakes at all, I'm sure you have seen daves posts, information, and pictures. Life happened and daves car sat for a number of years, and last weekend I picked it up from him, and I'm in the process of bringing it back to its former glory, and getting it back up and running strong. It ate up a distributor gear back in 2010 or 2011 and has been sitting since. I drained the fuel, oil, cut the filter open, and threw fresh fluids in it, a new distributor, battery, and got it running yesterday. There is a couple small issues that need to be worked out and I'm not sure what is causing what's going on, but one by one I will get the problems straightened out.
The motor is a ZZ4 short block, comp 224/230 hydraulic roller, after the 1.6's it's in the low .600 lift range on a 112lsa, 195 AFR heads, the SLP t ram, Arizona speed 52mm TB, not sure on injector size, SLP headers, and exhaust. It has a 2500-2600ish stall converter, plenty of stall for the cam, not too much for the street, and I can foot brake it to about 2000-2100ish.
Timing. I'm not sure where it should be set as it's a pretty hot 350 in the car. It seems to like about 12 degrees with the brown wire unplugged. Is that too much? It has a stock distributor, an MSD coil, and an MSD 6AL box
fuel system. It has a 255 walbro in the tank, and I'm thinking the fuel system is dirty from old fuel. What should I run for a fuel system cleaner through it? I'm hoping to not have to tear it apart and rebuild the injectors or anything.
Now the issue.. it wants to hunt for an idle real bad when it's cold, and it seems to be loading up a little bit at an idle. Then when you get on it, it starts stumbling real bad at about 3000rpm under hard load. Sometimes it will just rip right up and fly to 6600 and sings super nice and makes a ton of power. But sometimes it gets that stumble and won't spin up past about 4000. It's also creating a ton of heat and pressure in the fuel tank. If I pull the cap off the car after driving it, there is a huge amount of pressure behind it and will blow air until it cools down. I'm thinking this has something to do with the stumble, but I could be wrong.
None the less the car runs again, and I am going to keep playing with it until I get it right, just looking for ideas about where to go with it.
Ship it to me so you don't have to deal with it?? LOL
I'd work on the fuel tank issue 1st and see where that goes. Then keep plugging away one at a time.
I'm going to try some injector cleaner and fill the tank with non ethanol, and maybe mix a little ATF in there as well for an added detergent as that has worked well for me before. I'm going to try going for a drive with the fuel cap off it as well just to see if that's the issue before I start diagnosing moving parts in the charcoal canister. Then if that doesn't cut the mustard then i think the next thing I'm going to try is pulling the MSD and just running the ignition stock. I have had plenty of MSD parts fail on me. The MSD box is mounted down on the frame rail really cleanly and the wiring is really nice, so if it works I will leave it as is. I'm just used to mounting my MSD products one particular way just out of habit, and that's firmly planted in the bottom of the garbage can lol
So tonight I put a bottle of fuel system cleaner in it, filled the tank, and went and put about 15-20 miles on it, then tried messing around with it. The tank seems to have way less pressure in it with a full tank, but the stumble is still there. I am starting to think it's ignition related. I'm going to pull the plugs tomorrow and have a look. It is still only under hard load tho. and the thing really likes timing it seems to run the best at 12-14 degrees initial. I unplugged the MSD and that made no difference either. If you just stand on the loud pedal until the stumble clears up then once it gets to about 5100 it clears up completely. But from 3200-5100 ish it really struggles. I'm going to keep digging. If anybody has any ideas I'm all ears! As I'm from the generation of "if I can't plug my scan tool in, I don't know how to fix it"
Which brand distributor did you go with? Check all the grounds to make sure they are all tight and in place. I had a similar issue and it ended up being a ground on the back of the drivers side head.
The replacement distributor was just a stock replacement, the brand was "world power systems" I will definitely check groundsand see what they look like or if possibly one was taken loose when they pulled the original distributor years ago.
I haven't had much time to work on the car this week, but I did find not one but TWO vacuum leaks. I drove it up and down the street in front of my shop and it seemed about 50% better atleast. I am going to put a vacuum gauge on it tomorrow while it's running, and plug it into the old smoke machine and see what we find. That would be a simple fix lol and explains why it wants to die in gear with 5 degrees of timing.
Might be the fuel tank issue, might not, but you can always try the fuel cap.
My 1992 TA was doing the same thing, building a ton of pressure in the tank. I had other issues (coolant temp sensor) that was loading it up with fuel, fouling the plugs, etc.
Changed the fuel tank cap, and the pressure issue in the tank immediately went away.
Probably not your issue, but you never know. Sometimes it actually is something simple.
So I messed around a little more. It has about 12in of vacuum at idle, still struggles to find an idle more times than not, i did get a code 42, and 43 out of it. I tried a new esc, and tried a new knock sensor, and tired it with the knock sensor unplugged all together and still breaks up under hard load. Not sure exactly where to go now. After plugging off almost all of the vacuum lines to the intake, the idle did get better, to the point where it will run at 6 degrees initial now. I have it at 9 degrees as it does sound a little mose crisp. I put the ignition back to how it was when I got it from dave, with all of the MSD components hooked back up and working.
Do you have any way to data log a run to see what its doing underload? With all that you have done to it it might come down to the tune.
Did you try a known good maf?
what kind of fuel pressure are you getting at the rail? A starting to fail fpr diaphragm will give you the same symptoms. Also are you getting any back firing if you let off the gas in the problem rpm range? Does it load up with fuel or smell of fuel if you let off in that rpm range as well?
I don't have anything to datalog it with, just an autoxray scan tool to monitor with. I haven't tried another maf, and fuel pressure is going to be the next thing I check, but the T ram has no port to check it at so I will have to make something to go inline and make that happen. I can get it to break up even just 2 footing it to bring it up hard on the stall converter so I will be able to watch fuel pressure that way. Talking with dave about the tune I don't think it's the actual tune itself, as it never had this problem before when he ran it.
I would focus on fuel side of things. With it sitting for a good part of 10 years I would concentrate on the items that fuel would gum up. Fpr, injectors fuel pump and filter.
On a side note. Are you getting any noise from the cat or cats? Does it even have cats still on it? If so the catalyst could have a partial clog only effecting it on hard acceleration. Just something to add to the checking list.
Ok so I didn't look hard enough the first time. It does have a fuel pressure test valve port. It's got 32psi at idle, 43psi at WOT when it's breaking up. The TPS is at .52v at idle and 4.6v at WOT. It smells pig rich at an idle when it's dead cold too, and still has a hard time recovering an idle. Once it recovers, then it will stay at 800rpm and sound great all day long, and under light load normal driving it recovers and idle perfectly and smoothly coming to stops.
sounds like a tuning issue, You might want to purchase a mates.net g1, burn2 and a few sst27sf512 chips. The extreme all cable works well too. There isn't much support with tuner pro rt to datalog with $32B mask. You should start over with the arap file and 89 $6E mask.
If I have to start tuning on it, then I will be pulling the T ram for my 92 first and tuning it for the HSR as that is the plan. I was trying to get it running as is first, as dave had this setup running just like this. I feel like personally the tune is close enough it should work as it did before it was parked. I'm not going to give up and swap intakes just yet. The inconsistencies are too much for me right now. Every once and a while it will just rip up and have no issues and same with the idle. and how it clears out at about 4800 is too weird.
I'm getting codes 42,43, and 45. I found the link tuned posted on code 43 on how to check what's going on there. Im going to run through all of that tomorrow and see what I can come up with.
I spoke with Charlie tonight. The car is still a MAF controlled computer with an Ed Wright chip that was made specifically for the last heads / cam / T-Ram setup that was in the car. Back about 7 years ago, right after putting the AFR heads and new cam in, the car ran pig rich intermittently. I had a thread on this site as well as on our local 3rd gen forums, cascade crew. I ran the car with a stock chip originally but kept getting a code for excessive air flow at the MAF. I had gutted the heat sink fins and polished the MAF. Ed Wright said they would fix the issue. They did, but they also disabled the ability for the MAF to trip a code. When I put a stock chip back in the car, it would trip the CEL for bad MAF. I replaced the MAF and the issue went away. That MAF only has about 150 miles on it, doesnt meen it's not bad though. Also keep in mind, every MAF car that has had the battery unplugged for awhile needs to relearn startup.
I recommend swapping out MAF's for a known working unit. I would also swap out the coil, if your sure the plugs, wires and MSD box or working. Unplug the battery for a half hour, make sure the engine is dead cold. Reconnect the battery, reach in and start it up. It will run like crap and probably die a couple of times, keep restarting it. It should idle on it's on after the 3rd time starting. DO NOT TOUCH THE THROTTLE. Let it warm up until it goes in top closed loop, you will notice the idle slowly improving. Then take it out and drive it. Vary the way you drive it, hammer on it, then get in to some light throttle stop traffic and go then hammer on it some more. It takes several hundred miles for the computer to figure out what the tune needs to run correctly. I would also recomend picking up a good scanner that allows you to see the BLM / AFR / Injector pulse width etc. I had one, but my brother loaned it out and I never got it back. I suspect OBD1 scanners are tough to find nowadays, maybe a friend has one?
I can say that it isnt the tune, it should run fine with the chip that is in it. Maybe not perfect, but better than what it is.
Charlie, I was going through my gang boxes today and found the AC radiator, lines that go from the pump to the firewall mounted box and an extra set of hood louvers. I still need to get the AC pump and condenser from my house, once I do I will let you know. As we discussed, I would love to take a road trip and come down and see you make passes in the car. Sounds like your close to getting it running right again. Keep plugging away, your not far from getting it running right.
I downloaded the manual for my autoxray and it looks like I can monitor more than I thought I could with it. I'm definitely going to try the MAF next, and do the battery unhook and start it and let it warm up without touching the throttle like you said. I am used to my Stock SD L98 in my 92 that idles like a Prius lol I have been using my foot to keep it idled up from dead cold which isn't helping the idle issue by the sounds of it. I agree the the tune isn't the real issue. I'm half wondering if it's in the new distributor I put in it. I'm going down to my shop to play with it some more tomorrow so we will see. I'm also going to watch knock retard when it's stumbling and see what that's doing.
So I disconnected the battery, did the start and die scenario and just like dave said on the third start it firgured itself out and idled fine and went into closed loop. At that point I swapped the MSD coil for the stock one to rule that out, and no difference. Plugged the MSD cool back in as it was originally, fired it, and it develops a strange squeal / squeak at an idle. Sounds like it's from the cam area, almost torque converter sounding from under the car. I shut it off, collected my thoughts and pulled the distributor. Sure enough, it's trying to eat up another distributor gear. I shove my bore scope down the hole again to stare at the cam and it looks totally fine still as it did the first time. It's not a billet cam, and I have only run bronze heads on billet cams. I'm wondering if I need to put a bronze gear on it possibly even tho it's a cast cam????
Talking with my dad about it, and now we are wondering if the cam is walking out of it. we have a machine shop and haven't seen it in a long while, but not to say it isn't possible that this thing has the cam trying to walk forward. I'm real tempted to pull the intake, valve covers, and back the rockers off it and check the camshaft end play on it. Possibly the retainer plate bolts have worked themselves out, or even worn the thrust on the retainerplate to where it's moving around. The T ram is coming off to go on my 92 1LE eventually anyways, and the ed Wright tune that's in the car is actually setup for the other camshaft that came with the car. I'm wondering if now is the time to pull the T ram, check the end play, and either swap cams, or shove it all back together with the HSR. I really wanted to run it down the drag strip with the T ram first before I swappws intakes, but I don't want to hurt the motor if there is an issue with the cam.
The distributor isn't in deep enough (wear pattern is low) and you need a melonized (sp) gear for the steel roller cam. Most steel cams don't have a cast gear pressed on.
I think the cam is moving away from the gear giving it that low pattern. I'm going to pull the intake tomorrow and investigate further. I'm not sure how I could make it engage further aside from machining the base of the distributor to put it down further. I'm looking at the pics of all the firehawks and it looks like they all have a big cap HEI on them, I'm wondering if they are a longer distributor. I'm going to compare tomorrow at the shop
I think the cam is moving away from the gear giving it that low pattern. I'm going to pull the intake tomorrow and investigate further. I'm not sure how I could make it engage further aside from machining the base of the distributor to put it down further. I'm looking at the pics of all the firehawks and it looks like they all have a big cap HEI on them, I'm wondering if they are a longer distributor. I'm going to compare tomorrow at the shop
Might want to make sure you don't have the goofy TBI distributor from the early 90's B-bodies. I ended up with one in my stash on accident, it's shorter than a normal TBI/TPI small cap HEI. The internet says they won't engage the oil pump drive sometimes.
The bronze gear is going to wear out quick if you daily the car. I used to have to replace mine every couple years until I switched over to the composite gear.
I just checked distributor length with the one that came out of the car and it's the same. Story goes with this car that it had a smaller cam, and trick flow heads on it for about 8,000 miles, then dave swapped to this bigger cam, and AFR's and it never really ran right, then ate up a distributor gear. I would have to think the manifold is the right height with a stock length distributor if it all worked with the other combination. I'm leaning towards cam movement and or just a manufacturer defect in the camshaft that's in it. I'm going to tear into it and and see what I find tonight. I have the smaller cam that dave had in it, he gave it to me with the car. If I don't find something dramatically wrong, I am going to just swap cams out, and drop the HSR on it as I don't want to do the intake twice. I have a feeling I'm going to find something fishy with the comp cam.
Charlie, Not sure how to check this, but I always wondered if the thicker deck on the AFR's pushed the intake up further and caused the gear to be eaten up. The cam card for the cam that is in it doesnt say pressed on Dist gear so I thought that was the problem. The cam walking forwards would cause what your seeing. If your pulling the intake, check the angle and deck to CL of the intake bolts against the TF heads. I used GM head gaskets with the TF heads, but went with COMETIC on the AFR swap. Not sure if this helps but something I always had in the back of my mind. I tried calling you back last night, give me a call tomorrow night if you want.
Wouldn’t you think if the deck height is tall looking at the gear pattern . The oil pump drive shat wouldn’t engauge far enough. I wonder if you could use another distributor and rear end gear marking compound and crank the engine over to see the pattern.
The drive pattern is barely 1/4? low, I'd bet the oil pump drive could be close to being out.
Maybe look at the oil pump shaft contact pattern on the old distributor to see if its deep or shallow?
The distributor gear I pulled out looked like the teeth wore almost all gone from bottom to top. But I do recall stabbing the distributor a couple of times and thinking it was weird I didnt hear that solid " thunk" when it dropped on to the oil pump drive shaft and the distributor shaft collar bottoming out on the intake. It could be the AFR recommended intake gaskets are too thick and wont let the intake sit low enough in the valley to fully engage the distributor? I put 8k miles on it with Trick Flow heads, a different cam and the same MSD Pro BIllet distributor with zero problems until swapping the heads and cam. If you took the Distr out of your 1LE car, measure the distance from the inatke Distr flange to the top of the cam distr gear, then check the same thing on the other car. It appears that the Distr isnt dropping all the way down because the intake is keeping it from doing so, or the cam is to far forward and not letting the Distr gear fully engage.
So tonight I compared the new distributor I put in the car to the MSD dave had in it, both the same length, next I compared to the standard big cap HEI.. same length. I pulled the T ram off, stuck my head down the hole and it looks to me like the cam is in the right spot compared to the 2 other SBC motors I have at my shop out of cars. But, it might be just playing a mind trick on me but it looks like the gear on the cam is smaller diameter than the other 2 I have. I'm going to setup a pilot for my dual bore gauge tomorrow and get an exact measurement, as well as back the rockers off, and measure the exact endplay of the camshaft before I dig into the front cover. I didn't have a lot of time tonight but will continue to dig at it throughout the week. Racing tomorrow night but will have more updates before the weekend
Charlie, keep digging. If that gear on the cam is smaller than a stock 350 has used for 50 years I'm going to go off on a certain well know cam manufacturer. The wear pattern on the Dist you dropped in clearly shows the Dist gear engaging less than half of the cam Dist drive gear. Maybe the cam is walking forward but I doubt it. Please keep us informed on what you find. Even if I caused it, share the outcome of the core cause.
Oh I definitely will keep digging! I'm in too far to stop now! For me, personally, I enjoy fixing things that are out of the ordinary. I like geeking out and finding problems, coming up with a game plan to fix it, and make it happen. I will have the cam out of it by the end of the weekend and I will know for sure what the issue is. I am going to set this cam side by side with the cam that was in the car previously, then once I have a definite answer on what the issue is, I will start putting it back together. I am leaning towards putting the other cam back in the car whether I find a problem with this cam or not, just hearing from you how much better the car ran with the chip that's setup for that combo. Dave, also do you think it would be a good idea to swap back to the 24# injectors from the white 36# ones if went with the smaller camshaft??
Made some pretty solid progress tonight on the car, I'll spend a couple more hours on it tomorrow after work and see if I can't get the cam out of it and start putting things back together. I'm also going to change the valve covers out to some cast aluminum dart ones I have around the shop, and put some real fancy spark plug wire looms, and throw all new standard black coolant hoses on the car, along with black plug wires. Trying to decide if I'm going to leave all of the MSD ignition on it or to take it off while I'm in here. Also considering changing the accessory drive to the later serpentine stuff, or maybe even low mount aftermarket stuff just to clean up the engine bay a little bit.
I got the camshaft out today, the gear is pretty messed up, but only on one side. I chucked the cam up in the lathe and its machined offcenter. The gear has .045" of runout on the teeth as it spins. It's not a billet cam, it's a cast iron piece. So I mounted the other crane cam that came with the car in my camshaft polisher, checked it for straight, and checked the runout on the gear and all is well with it. I threw a fresh micropolish on it just to make it fresh before I plop it in and start putting it all back together.
No matter what intake you use, you’re gonna have to get it tuned or tuned it yourself with the proper tuning equipment. If not, you will be disappointed with the power performance.
I did get the numbers, and took pics of the end, and called crane and they told me all they could give me for info was that it was a custom grind and they didn't have records that far back. I looked through the file of papers dave gave me with the car and there unfortunately wasn't any information on that particular cam. Dave told me it was really close to the firehawk cam, and that it was part of a low 12 second t ram combo he had found in a GM high tech magazine with the TFS heads.
06-17-2018, 05:56 PM
