89vette

Just when I think I'm getting it, I have another new problem. Isn't that nice. Actually this problem seems to come and go somewhat. Prom tuning does not seem to rid the problem. I actually had this problem prior to the speed density conversion. Here it is:

Fourth gear (manual). Slow car down to and drop RPMs to 1200 or so. Give it just enough throttle to not envoke PE, about 30%. It runs like its running on seven cylinders or less. Real rough and missing. While its running rough flooring it does not make it go away. WTH? At first I recorded a lean condition, added fuel to the upper KPA areas and it does the same thing. Even with high O2 volts it does it. It won't clear up until usually until load drops and RPMS increase.

If it weren't for this, the car would be running good. WOT and what not is fine. Even now. Its low RPM, hi load. Next step is to tape the fuel pressure guage to the windshield.

I literially can not take this car anymore. I'm seriously considering selling if if I ever get it running decent.

Jason

branz28

whats your fuel pressure?

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Gutted cat
-!AIR
-Gutted Air Boxes

89vette

I taped the guage to the windshield and
I'm getting good pressue at high maps (45). I did a little experiment and jambed in 20% more fuel at the 80 and 90 KPA areas just to see what would happen. O2 volts were well over 900 while its missing. Like I said, even PE enabled it misses. It's acting like a fouled plug. The old rapid fires and the new ac delcos in now did the same thing. It used to be an intermittant problem but now its all the time. How do I tell if I'm fouling a plug? Could it be a bad injector on the right bank that has no O2? i pulled an injector to see if it acts the same and it feels different. It misses then after a while it clears up. Like I said, feels like a plug fouling and then firing again. I have really had it to say the least. The Diacom recoring of the events show no signs of abnormality. Timing is advancing, O2 volts good, no knock, high pulse widths, etc. Could a bad ignition module act like this with weak spark casuing a fouling condition? Whatever it is it seems to be getting worse. Heat might play a role too but I can't prove that just yet.

I need help guys.
Jason

Grim Reaper

Could be a pick up coil in the distributor. Have you ever changed that?

I am assuming that you have a new distributor cap and plug wires.

89vette

Glenn. I just took off the cap for inspection and the rotor screws backed out. It was just flopping in there. I figured that had to be the problem. I installed a new cap and rotor. Guess what? problem is still there. I took a long recording in fourth with my foot mashed on the gas, and my other foot holing it back with brake. It would have sat there all day chugging and missing if I let it. O2 volts were over 900 the whole time. I changed the pick up coil about 3 years ago when I had another problem so I have to assume is still good. Where can I go from here? There is fuel we know that. Even if one injector was bad I wouldn't expect it to run this lousy. All I can say is I really hate this car. I'm thinking of putting the TPI intake back on and the MAF and seling the pig. I hate I, I hate it, I hate it!

Grim Reaper

Try the reverse, try leaning it a bit.

What are your knock counts looking like?

leirch

I know on my car, when i'm in the low rpms i have basically "no" power. Once i get into the power band it picks right up. Another thing you have to remember is that your driving a stick and in 4th gear at those rpms, i wouldn't imagine you'd have a whole lot of pick up. Without seeing the problem first hand... opinions come into play as to what one thinks is really going on.

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

slowTA

iTrader: (1)

WOW.... your rotor bolts backed out too!!!! That happend to me a couple of times (with the coil in cap design right?) I thought I fixed it when I swapped in a different distributor but I just noticed it again today... it first happend when I installed a Hypertech high energy cap and coil with the nylon screws. I expected them to back out so then I swapped to metal screws and it still happend... then I swapped the cap and rotor with accel pieces and once again there all the way out. At least this time the rotor wasn't jammed into the side of the cap.

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'86 TA, T-tops, T-5, 3.73, 4 wheel disks 350, compucam 2040, performer intake,SLP Headers, 3" race magnum muffler, 1.6 Comp rockers, Ripper shifter, perf. friction pads, Hypertech ignition, Earls brake hoses, Hotchkis springs, Tokico Illumina 5 adjustable shocks and struts, Lakewood panhard and trailing arms
14.50@ 97

89vette

Glenn, At first it was lean with low o2 volts but even in PE it still did it. Adding 20% fuel did nothing except bring the O2 volts up and make my tailpipes black. If I slowly give it throttle and don't go into hi load areas, it has less of a chance of doing it. Once it starts missing bad, quickly taking your foot off the throttle and mashing it again, it will still miss. Its like it has to clear something out. This doesn't make and sense. I pulled all the plugs and they look fine with no evidence of fouling or deposits or wetness.

I figured for sure the loose rotor was the culprit. I removed the cap again to visually inspect the pick up coil for any damage or anything and it looks perfect. i had this same problem with my MAF setup a couple of times but it went away. I'm fairly cinvinced that I'm going to sell the Miniram (my car ran good before I installed it) in favor for a hi flwo TPI setup or most likely a Super Ram. I had a Superram at one time and it ran good on my car. None of this tip in crap I have been battling for a year! The tip in problem is why I switched to speed density in the first place. Now I have it sometimes and sometimes I don't. I don't know. My brain is fried, my wallet is smoking and I'm ready to give up all this perrformance stuff. I like my old hi flow TPI setup the best.

Take care and any thoughts as always are appreciated.

89vette

Also my knock counts are only a few degrees initially then it clears up. Timing was as low as 9 degrees rel to ref or 6 degrees. When I run the chip without the added fuel, the O2's oscillate when not in PE. If I add more timing most likely it will just retard it out right?

nicmike85

Maybe the rotary button bent one of the posts in the cap. Can you pinpoint this to one cylinder or not. If you have a different color plug then it's probably mechanical. If it bounces around to different cylinders it's in the ignition. Does your datalog show you all the cylinders (injectors).

Bobalos

FWIW, It sounds to me like there is an ignition problem. If I recall right you said that it worked OK for some time, & then it was doing it mostly when NOT in PE & PE was OK. then it was when NOT in PE & when in PE. this makes me think that it is getting worse.

If this is an ignition problem, I would try to change the coil & wires. If that does not help then try to gap the plugs +5 thousands (Make the coil work harder). If that does not help, try changing the PU coil in the distributor, I have seen them do strange things in GM distributors. (I think that Glenn suggested this).

If you have O2's of 900 then there is bound to NOT have a lack of gas. consider that W/the car in 4th & the RPM's low you are working the motor hard in an area that it does not really want to run. if you are not getting any knock counts, maybe adding a touch of timing might help as well, but I would not count on a big difference. But every bit of help will make it feel better.

You did not mention what cam you have in it. When does the cam start to come on? is it about this same area? if so then this might be compounding the problem.

My car does something very similar to this, but it is a 700R4 so it only does it for a little while & then it down shifts & goes into PE & off she goes.

hth's

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Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
<><

89vette

Yes it seems to be gettign worse. Enabling PE dd not help before either. It was only a couple times before and it went away so I thought nothing of it. The motor may not want to run there but there is no reason to do what its doing. PE should clear it up if it were lean which is not. I did swap out the cap, cil and rotor today with no luck. Pulled all plugs and they look good. Wires are in good condition. Knock is maybe 2-3 degrees.

Neil

Did you check the resistance of your spark plug wires? Also, check for vacuum leaks. I had a stupid hesitation problem and it was my intake manifold gasket, it was partly "sucked" in.
Good Luck

Greenshamrock77

I had this same problem on an 89 blazer 4.3 TBI. Everything checked out fine. Turned out to be the spark plug wires. They were not arking to the block or anything, but had excessive resistance. I turned off the shop lights, ran it at night and the spark plug wires were myriads of light. When you see this, it is an indicator of high resistance. I replaced the wires, and the problem completely disappeared

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82' Z-28. 327" w/ flat tops. 216/228/112LS. Pocket ported 041 heads 1.94/1.50 SS valves. World Class T-5 from a 91'. Best run? Runs with 2001 vette to 150mph! Soon to be converted over to TPI w/ supercharger.

89vette

I'll check that next. What should I see as far as resistance?

steve8586iroc

89vette, it depends on what plug wires you are running. Stock factory wires have around 3000 to 4000 ohms/ft. Most aftermarket wires have around 1000 to 2000 ohms /ft. The best wires have from 50 to 500 ohms/ft. I can't say that I'm exact on all the numbers but I shouldn't be far off.

Steve

89vette

Thanks. I am running GMPP 8mm wires. I'll check them out soon. I did find one with a crack in the boot that is really close to the header pipe. But I saw no signs of arching (black spots).

Jason

Hunter Motorsports

It doesn't take much for a wire to be bad, and cause you all kinds of problems. Like others have said, check the resistance. If you do indeed have a cracked boot, it may be arcing, but you may not be able to see any evidence of it. Just get another long spark plug wire that you know is good and start swapping them one by one. If that fails, check the resistance of your injector coils. If one is going bad it could cause this kind of problem. Resistance should be between 13 and 16 ohms.

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Karl Hunter
Hunter Motorsports
Vancouver, B.C. CANADA

FastBroker

I'd buy a cap and rotor too if I found the thing loose and it was spinning that way! Cheap and probably needed... Also, as stated above, check the pickup coil resistance while in the dist. Easy test and piece of mind is good. Just buy new plug wires and plugs if you could even consider them as suspect/older... Not too expensive and the associated mileage and performance improvements should make you happy... Just my O2

Bobalos

I have had PU coils Ohm out good, but changing them helped drivability problems. I dont know why, I can only assume there were problems when real current was going through them (although not a lot), it is magnetism & gause & all that so........ I was not paying much attn that semester.

BW

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Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
<><

Grim Reaper

Jason, it looks like you have a lot of people watching your thread...possibly hoping to cash in on that Miniram if you dump it.

YOU VULTURES!

But it seems everyone is leaning to electrical too.

89vette

I have to be honest with you. I don't see what everyone sees in the Miniram. Unless you drag race which I don't or have a solid cam and a motor that revs to 7000 which I don't, then to me the more torque the better. Before with my 350 and ported heads and little Crane cam and a Super Ram, my motor pulled strong to about 5500. It had a nice thrust of torque. Actually my 396 with a Miniram versus my 350 and Large tube runner TPI has 60 more horses at the wheels but only 20 ft lbs of torque more. Sure if I ever got my tuning issues worked out I might keep the Miniram. I have more people telling me to keep it than to dump it. The Super is more expensive than the Minoram anyway by $8.00. LPE just raised their prices by $100.00. Then there is the issue with the low speed air turbulance. The front cylinders run leaner than the rear.

I just don't see what all the hype is. Maybe I'm just bitter. Someone offered me polished Super Ram and big mouth base as an even swap. That sounds like a fair deal.

Jason

Hunter Motorsports

WOW! That sounds like a SMOKIN deal if you are on the receiving end - of the Mini-Ram that is.

Dump the Mini-Ram???!!?? WTF are you thinking??? O.K. Sorry for the tone, and I don't pretend to fully understand your situation, cause I don't have all the details, but before you go and do something rash, like trading the best small block EFI intake manifold there is (personal opinion) for a more complicated, heavier, more restrictive PITA manifold setup (personal opinion) - consider fully the reasons you are doing it. Are you planning to bolt the Superram on and have all your problems disappear? I dont think so! This problem you are having has absolutely nothing to do with the fact that there is a Mini-Ram bolted to the top of the engine. The problem lies elsewhere, so don't blame the manifold. You will curse yourself for trading whenever you have to work on the Superram. They are a total Pain. I am not saying that they are no good, they do make excellent torque numbers, but you already have 350 torque-producing cubes under the hood - are you short on torque with the Mini-Ram?
I have said it before, so has Traxion, so have others... It is all in the combination.
Build the combination right with the Mini-Ram and you will far exceed anything the Superram can do. The car will be just plain faster. The Mini-Ram provides a broader torque curve, which leads to better overall power production. Superram cars feel fast (they are fast) because of the big fat torque curve, but again because of the long runners, overall power production suffers.

You have the right car for the Mimi-Ram (Manual) just keep pluggin away, get your problems fixed and stay focused on the real issues. In the long run you will not be dissappointed.

Just my $.02 worth here, not trying to ruffle any feathers here, just offering my (experienced) oppinion.

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Karl Hunter
Hunter Motorsports
Vancouver, B.C. CANADA

hectorsn

I couldn't agree with you more. I have a 400 that makes over 400 rwtq from 3500 to 5500 and peak is 420 rwtq. If that's not flat, I don't know what is! Oh yeah, that's with a single plane Victor Jr. and a 750 carb and a fairly big cam. Also, power below 3500 is exceptional and since I drive this thing a lot on the street, it's a good thing. I am positive that it can be better with EFI. It's going to be tough, as the car really drives well, but it will be better.

89vette

Whoa! The overwhelming consensus from this forum and the Corvette Forum is that I'm nuts! OK, I'm going to give the Miniram another try. I have alot of off the Forum help from people that really want to see this car meet its potential. On the bright side (I'm hoping) I did find a plug wire that has the metal end sticking out of the bend in the 90 degree boot. This is the plug wire that has the heat sock that is really close the the header. The way it sticks out and for how close its to the header (it basically touches it) it just HAD to be arcing. I'm going to replace it and give it a go.
Thanks for all the advise guys. It really does help. Lets all hope that this wire is the problem.

Jason

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89 Six Speed FX3 coupe
More Performance 396cid specs:
Callies 4340 crank 3.875 stroke
Lunati Pro-Mod 5.85" rods
SRP Pistons 14cc dish
Comp Cams Custom cam 550 lift 220/229 duration
10.8:1 compression
AFR 195 competition ported heads
Miniram and TPIS 1 3/4" headers
Speed Density conversion in process

BOWTYE8

ditto to above on the MR. Check those wires.
I have also done this . some may not agree.
Pull all your plugs. They all look even light tan or ???
Then I have turned up my fuel press while idle . say to 55lb.
Pull all plugs. May shure they all darken up.
If one it still lite or soaked wet. That could be your weak cyclinder, ihnjector or wire.

Keep that mininram. You have a bullit proof motor there. Good to 6500. ---No sweat --

You should also be making 400+rwhp not the 320 like on the last dyno run.

Hang in there.

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85 vette,383,miniram,ZF6,4.10's..best ET 11.56@119.00 60' 1.59
w/100HP nirous 11.05@127
http://geocities.com/bowtie8
http://bowtye8.tzo.com

Grumpy

Untill you get in there and open up the plenum, the minram will have issues.

Take the Linenfelter design, and increase the volume of its plenum, and couple other lil things and it will run with or away from the miniram.

But this is gettin quite off topic.

89vette

Oooooooo Grump, thems fightins words!

Hunter Motorsports

Fightin words indeed.

Cube for cube the Mini-Ram makes more power than the Superram. Hands down, plain and simple. And issues???!?!? WHAT issues?

And as far as the Mini-Ram being short on plenum volume, I don't see where that is coming from. If you measured the volume of the plenum I am sure it would be smaller than the Superram, but probably not that much smaller. The Superram plenum may look huge, but it is quite thin inside, so looks ARE deceiving in this case. In either case, I am sure that the Mini-Ram plenum is considerably larger than that of almost any carburated setup (E.G. Victor Jr. which is an awsome manifold) so - again What issues?

Anyway, I don't want to get off on a rant here, so I'll stop now. Most people on this site know that I am one of the biggest Mini-Ram supporters out there, so YES I am biased, but for good reason.

Jump in here anytime TRAXION - defent that manifold that is bolted to the top of your motor!

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Karl Hunter
Hunter Motorsports
Vancouver, B.C. CANADA

Grumpy

[QUOTE]
Cube for cube the Mini-Ram makes more power than the Superram. Hands down, plain and simple.

In stock form.

And as far as the Mini-Ram being short on plenum volume, I don't see where that is coming from. If you measured the volume of the plenum I am sure it would be smaller than the Superram, but probably not that much smaller. The Superram plenum may look huge, but it is quite thin inside, so looks ARE deceiving in this case. In either case, I am sure that the Mini-Ram plenum is considerably larger than that of almost any carburated setup (E.G. Victor Jr. which is an awsome manifold) so - again What issues?

Superram is about 380 CI, what's the mini?

Being biased, only closes one to the actual facts.

It would be rather easy to do a manifold to out do either manifold.

While folks talk about runner lenght in relationship to operating range, the lenght has alot to do with how an engine acclerates, so if your into shear Dyno work the Miniram can look to be a great performer.

The superram miniram debate is engine specific (to include application).

TRAXION

Bruce is absolutely correct on the main issue with the MR .... the MR is down on some serious plenum volume. But, you have to ask yourself the question about what manifold you want to run with what is *available* on the market. The MR would be much much more kickarss if it had more plenum volume. This would definitely solve A LOT of the MAF guys PROM problems with the MiniRam and would also give more torque at the lower RPMs. However, I still choose the MR because BOTH the MR and the SR have issues. I, personally, would rather deal with the MR and its problems than the SR and its problems.

This is getting off topic though. So, lets keep this side discussion to a minimum. I felt it necessary to jump in here and support the MiniRam problem of low plenum volume. That is very very true. More plenum volume would make the MR a truly kickarss manifold.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

Grim Reaper

I think I have convinced Jason (89Vette) to give the Miniram a second chance.

But, I think Grumpy makes some excellent points...1) What is your application and 2) Proper tuning.

89vette

Yes Glenn has helped me a great deal off the forum. A GREAT deal. Me thinks me keeps the Miniram now. My bin is very close and my problem that started this thread has seemed to disappear. Weather it was bin related or the suspected bad plug wire that I replaced I do not know. What I do know is that I'm back on track and I could not have done it (my stress levels are too high right now) without Glenn's help. Hats off. I hope that he does not get bombarded by prom beggers as a result of this post.