Dscott

Ive been searching around threads for two solid nights and haven't seen what I'm looking for....

I have a stock 89 Iroc 305 TPI 5 spd with air 4 whl disc 3:42. A year ago or so it was like someone turned a switch and the car went from running amazing to running like s hit. Changed injectors, changed distributors blah blah blah ....same. Professional mechanics cant even figure it out.

I found the TPI VERY hard to work on probably part of it was working with 20 y/o stiff/siezed fasteners everywhere. I couldnt believe you have to take the whole top end of the TPI off to change injectors. Anyway Im looking for an aftermarket set up that I could use with minimal installation/wiring hassle. Smog legal would be nice too. I looked at the Fast efi but by the time I got the TPI wiring conversion kit Id be into 3K....too much. Same with LS swaps, too much $$ also. Throttle Body type set ups are not out of the question either. A guy around here has a Holley Pro Jection set up for sale for $500, could I make that work?

I see the threads on the Super Ram and Mini Ram but they seem to be geared towards more modified engines and are really too much for a stockish 305 maybe 350. I want to keep the T5. I dont want a race car I have a Nascar for that. I want a nice driver with nice paint where the A/C works, nice stereo/interior, some SFCs etc and would not hesitate to hop in and drive to Florida at a moments notice. Heres a pic of the car, except for the dent the body is mint, floors same. Thanks D

jmd

iTrader: (4)

You really should post here in the right forum about how to troubleshoot your car and consider getting the factory service manuals so you can better troubleshoot, rather than giving up based on mechanics who aren't excellent diagnosticians.

The EFI systems you mention are not smog legal, nor would they gain you anything on an LB9.

When you get it figured out, and if you still want some gains, the emissions legal intake manifold is a Super Ram which can be used with the TPI wiring & ECM. But again, that's not going to take care of the issue at hand.

Or, do a complete (with emissions) LT1 or LS1 swap and go T56.

There are a lot of "not worth changing just one thing" ways to go about this. You're reasonable in saying "I want... but I don't want to lose this...." but that's the thing with car mods. No one wants to dump $$$$$$$ into something by changing everything all at once. But doing that via a late model drivetrain is sometimes the way to do things when drivability, reliability, economy and emissions are all expected together.

You'd probably be better off chipping away at determining a diagnosis of your car from the sound of what you're saying.

That's the short and the sweet of it.

Dscott

jmd...I know there are pages and pages of guys with TPI issues many of them never get resolved and are on an endless repair merry go round and are not confident to take the car any real distance. I dont want to end up like that. Im looking to get rid of that system and fix the car for good. The guy I had working on it fixes everything from diesel pick ups to late model Porsches. He is the guy all the other mechanics in the area call when they cant figure something out. If I gave up a little performance with one of these systems its better than the car sitting in my shop just taking up space. Thanks for taking the time to reply

anesthes

iTrader: (12)

The problem isn't the intake, it's the mechanic diagnosing the issue. I'm moving this to the TPI forum. Maybe someone their can help you if you provide some technical details as to what your car is doing.

-- Joe

spurgeon76

First question is does this car have to stay smog legal? If not, I think that the Stealth Ram would be your best bet. It's cheaper than any other intake, is easier to work on, and you can access the injectors without pulling the intake apart.

built91Z28

I don't see what you would expect to gain by ditching the TPI. The intake manifold moves air. Thats it. It's not responsible for any of the issues you are having. If you stay EFI, then any of the other intakes are going to rely on the same sensors you have now. Nothing changes there.

MadCelt

Well said.

The only way around this is to either dump EFI altogether (NOOOO!) or else go with an aftermarket EFI/ECM package such as some of the FAAST products that use different sensors.

Your issue is correctable, you just need to find someone who actually knows about TPI.

jmd

iTrader: (4)

Let me say this. Be like me and be lazy and cheap. If a part is in question, do I buy a new one without troubleshooting? Usually not. Do I get off my butt, walk to the bookshelf where my Helms manuals are kept? Usually not. I grab the same part from a similar car. Now, I don't expect you to have two of the same car. But the point is, you need some sort of methodology to fix it and it is fixable. For accurate, non-redundant repairs, following the factory service manuals to a tee is the way to go. But it can be terse to read and follow all those procedures. And none of us has all the tools listed, nor the immediate knowledge of what interchanges with them, so there are snags. So what's next?

I searched your posts last night. Lots of Chevelle. No "help me with my TPI for a couple years." So let's thank Joe for the thread-move.

Now, how is the running poorly happening? At idle? Part throttle? Full throttle? After a shift? Is it different in neutral while rolling 45mph than at idle, 0mph?

Re: your parts changes: Great, you've ruled out a couple things, we think. Have you had a scanner on it? Sometimes when I don't feel like working on something it still helps to take a video of the data screens on the scanner so I can review it later when I have more time. And that may be a needle in a haystack or for you a PITA if you don't know what the values are generally supposed to be.

But, you gotta start somewhere. One minor test & a post a day will get you fixed.

Dscott

So I get moved to the TPI section so you're going to "force" me to fix it LOL!

Well FWIW like I said the car ran great for ages, we wouldnt think twice of driving it 3hrs one way to the cottage. Then one day drove to the mall (all legal speeds, no choice) was in there for about a half hour, came out, hopped in, drove off and it was a little off like it had a bad plug or something. Anyway, parked it in the garage. Came out to drive it a couple of days later ran like total s hit at all rpm in all gears like it had 4 bad cyls. Ohmed out injectors IIRC 2 were open, 3 were out of spec and three were ok.

Ordered new injectors from Southside, put them in, total PITA I might add, finally got them in put on adj fuel reg that I also ordered. Two or three of them leaked, called Southside back the person said "Hmmmm....we sell tons of those kits, every once in awhile we get a set that leaks". Anyway got it started up,adjusted fuel pressure, same, no difference. Had it towed down to the mechanics he put it on his giant Snap On scope, worked on it for a whole day, found slack in the distributor, changed it, a little better but the same basic problem like its only running on 4 cyls.

And yes the car needs to be smog legal and yes the car has sat for a couple of yrs.

I already have one large project going on with the Chevelle it is a MAJOR build, I don't have the patience for another one.

Damon

So you still have leaky injectors in it or you swapped out set #2 with set #3 already (replacements from Southside for the first bad set they sent you)?

Did you change the fuel filter before you put in set #2? I always change the filter and run it for a few minutes with the old injectors to minimize the chance of old fuel line crud plugging up the new injectors.

FireDemonSiC

What exactly is your TPI doing to run like crap?

Simply swapping the TPI out for a different intake will not get you much if anything on an otherwise stock 305 (Or even 350 for that matter).

The thing that most people don't realize is that the CAMSHAFT the engine came with stock was matched to the powerband of the TPI. So just because you toss on a shorter runner intake such as a mini or stealthram doesn't mean you pick up loads of top-end. The intake has much headroom for RPM yes but it doesn't mean the cam which was designed to make power in the low and midrange where the TPI shines at is going to be operating the valves efficiently enough to make power that high. In fact you might even loose some performance because you have now put an intake that was designed to peak torque probably around 4500 - 4800 RPM and pull strong til 6700RPM or so on an engine with a cam that will peak torque in the low 3xxx range and make horsepower until around 5000 or so.

If you're dead set on swapping intakes you need to mate it with the proper cam and possibly even look at some heads if you plan on spinning some decent RPM.

Orr89RocZ

iTrader: (20)

Lt1's use same kinda of cam on an intake that will support 7k rpms.

Hsr on my L98 on stock cam moved powerband from 4200-4400 rpm peaks to 5000 rpm peak. Made bunch more power

In general tho, you want all components to match intended rpm ranges for the most efficient engine package

FireDemonSiC

A stock LT1 will not rev 7000rpm due to...well the rest of the motor LOL. But the stock cam isn't making that kind of power. To have a cam that would make power at 7000rpm I imagine would have the bottom end of a honda for practical street purposes.

I shouldn't have said little to no gain, that was a bit exacerbated.

Cam might go a little over 5000rpm yes but that doesn't mean you're going to be taking full advantage of an intake that will REALLY shine around 6500 - 7000rpm. Trust me. I hogged the hell out of my TPI runners and plenum at the same time I installed a ported base manifold, but neglected to do a cam swap because I decided that it was money "Poorly spent" since I was building a whole new longblock.

Now I lost a bit of bottom end on the stock cam and stroke due to the runner change and while I can tell it moves air a TON better up top I have a peanut cam in my current motor that completely shuts down at 4500rpm just as I can feel the power start to come on. With the new engine at least a year and a half away, it would have been wise to just spend the extra $200 on a cam I could have gotten good use out of. It was kind of foolish to do all that work to the point of a cam swap being a timing chain cover, oil pan and radiator away just to put it all back together and be disappointed.

Dscott

No I didnt change the fuel filter and it still has the leaky injectors and I havnt touched the car in over a year we are not on speaking terms.

As posted earlier I want to ditch the TPI to get something that will WORK (actually change it to anything that will WORK) and be easier to work on. I am not interested particularly in "gains"

It runs like it is got a couple of dead cyls but it doesnt. I seen it on my guys scope theyre all good. He can press buttons and knock out individual cyls one by one.

FireDemonSiC

As has been stated before, by simply getting rid of the TPI for another EFI system is not going to make your job any easier minus the dis/re-assembly part. They still utilize all the same o2, MAF/MAP, TPS, IAC, knock etc. sensors that TPI does. Even the injectors are the same (Unless you go to something like TBI)! It is not the same as swapping from TPI to a carb.

You need to get accustomed to all the sensors and figuring out what the problem is yourself or you will be right back in the same situation with the new EFI setup. I would start with replacing the injectors ($200 from southbay with a fuel rail rebuild kit). From there, obviously new plugs, replace the o2 sensor ($20 can't hurt) and I would HIGHLY recommend checking the diaphragm in the fuel pressure regulator (You can usually tell if It's blown by removing the small vac line that attaches to it and checking for fuel in the line).

What exactly is it doing besides running like half the engine is missing? Does it hesitate, idle rough, throw codes or pop/backfire through the intake?

Johnny Blaze

iTrader: (15)

You realize your dealing with a 20 plus year old car right? There is nothing wrong with the TPI, literally hundreds of thousands of cars are built with them, and they did just fine.

Orr89RocZ

iTrader: (20)

As everyone stated a manifold swap is not going to fix electrical or mechanical issues. If it used to run and then all of a sudden doesnt, that should tell you something is wrong with some electrical or mechanical aspect of motor and not an intake manifold.

theNMBR27

If the injectors are still leaking change those first. Fix known issues now then deal with the rest later. One symptom may cover up another so it is possible other things are off. I've had shorted/ leaking injectors and I know it's not fun but after that the car ran phenomenally.

thewhitestripes

In my experience working on a TPI is like artwork. I like to heat up the garage, get some music going, pop an Advil for my back, disregard all my power tools and dig in one bolt at a time. it's by far the least stressful way to go. And don't give yourself a time limit either. That always puts un needed stress on me. I feel your pain when it comes to tpi they are hard to work on theirs no doubt about it. But if you go in with the right mind set its not to bad. Try adjusting your injectors in the manifold and fuel rail then check to see if they leak, you don't need to put it all back together to check the fuel pressure. I had two leaky injectors and that worked for me. I know it's a longshot but have you checked your cat converter? Mine welded itself together and it felt like a 4cyl too because of the retricive exhaust flow.

jjcuff1

I built a 300zx with turbo and MAF and similar ram style intake and it was a PITA. I had the same on/off issues and ultimately after doing tune up it still happened. I finally figured out it was 2 things.

1: The o2 sensor was definitely bad and caused massive lean/rich conditions. Voltages checks out on these old ones o looked good and I didnt change until I did otehr things. Installed a/f wideband and found the o2 was shot. replaced and dialed in fuel and it was a 14point7 wideband kit and that solved my problems BUT....

Before I found the problem I fixed symptoms and I bet this caused my immediate poor running. Since it ran rich at idle like 10-11. i Had a lot of fuel carbon backing up and sooting up the MAF that was hosed but since it was a MAF it was finicky. I cleaned I ohm tested and just end up with new one. Ran fine for month until got dirty again then it would stumble, fall on its face at times etc sound like it was missing.

It was my O2 and MAF and fuel system.

The missing cyl sound and feeling is probably you running way too lean and detonating. it was in my car.

You changing the injectors was probably good they were probably clogged anyway but no you are getting more fuel, IE rich and bogging, sooting up even more throwing your MAF out even more.

Other part of the equation was the TPS

so check MAF, 02, and TPS and you should find your problem