92RS-HeritageEd

iTrader: (2)

I apologize in advance, and it is not my intention to be remedial if there's a ongoing thread or sticky...but can someone share some budget friendly, bolt on mods, for those WITHOUT access to machine shops, or related equipment? OR Can someone share a link or two with me to get me going in the correct direction. I tried reviewing "The Ultimate TBI MOD's" Part 1 & 2 but beyond the Open Air Cleaner things seemed to begin exceeding my wrenching skill level...

Ridicule not needed or wanted, Assistance is however greatly appreciated!

mikeyt

I've got the same car in red. If yours is bone stock like mine there are things you can do to wrench on it. I am doing a lot of work on mine replacing the heads along with a lot of other things. For you, I would say remove the factory exhaust manifolds, replace with headers and new down pipe and air management including air pump-there is a gm delete pulley available on ebay for $50, get a chip to start. Depending on your wallet your looking about 600-800 depending on what you want to spend.

92RS-HeritageEd

iTrader: (2)

Well when I bought mine it had no exhaust from the Cat Back so I threw a Walker System on w/ SoundFx muffler. So you're saying pull the entire SMOG/AIR setup and drop in some Hooker Headers or a comparable brand like Summit, JEG's, etc. I can also afford the delete pulley, but but when you mentioned $600-$800 we had a Code Brown in my pants lol. I've also read several threads on "Performance Chips" but....again that exceeded my ECM, and performance tuning knowledge. Are these "Chips" like RAM in PC or laptop that I can just slap in?

mikeyt

I'm putting a set of Flowtech ceramic headers and Y pipe on mine. You'll hear several things about them, some good-some bad. Whatever you do replace the bolts-you'll need to. Make sure you bag the one's that have brackets on them. I'm using a shorty header so it can bolt up to factory converter, really so I can keep the configuration. Yes the chips are that way, you remove them from your ECM and replace them. The headers are depending what you want to spend. Mine ran me $575 with the down pipe.

92RS_Ttop

iTrader: (3)

Check out tbichips.com. Lots of good info on there, even though the site is written for fullsize Chevy/GMC trucks, the same principles apply to our TBI engines.

robertfrank

iTrader: (27)

Just read my cardomain. I need to update it but it has alot of good info.

92RS-HeritageEd

iTrader: (2)

Thank you, I'm looking it over now!

dmccain

iTrader: (2)

I can tell you going from 2.73 to 3.73 in my L03 was a huge improvement. Didn't really hurt my gas mileage but maybe 1-2 MPG at most. A custom chip seemed to help some but don't expect huge gains. Headers and y-pipe will be your best choice though. Only reason I haven't done that route is I may be swapping my 305 out in the next year or two.

92RS-HeritageEd

iTrader: (2)

I wanted my 1st keeper ThirdGen to remain a #'s matching vehicle dmccain, so no engine swap on the 92 for me (may do a full re-build next year). I am actively looking for another ThirdGen though, that I can go all out on. Where I'm located there aren't requirements for SMOG/AIR equipment I've come to find out so I'll likely begin the removal process with header installation here within the next month.

mikeyt

Do not use the Flowtech headers and y pipe combo, they're not both ceramic coated-just the headers are. When I opened the box and saw this I called Jegs got them to pay for the shipping back and they're sending me a set that has both parts ceramic coated at no extra charge.

92RS-HeritageEd

iTrader: (2)

Funny you say that mikeyt, I was looking at Hedman (Direct Fit Street / Strip) Headers. I believe there the 68460's. Through out my search of threads and sticky's no one has said if they are truly direct fit as in bolt right up to my factory Y-Pipe. Can't tell on the JEGS site...

mikeyt

The Headman part numbers are 68476 for the headers and 17678 for the Y pipe. From everything I've researched I've fount that none of them are direct bolt without grinding of a small section of your a/c bracket at the bottom and I believe the same for the power steering bracket. I was hoping not to do that myself but that's what it takes. I called Headman today and they said they are about 4 weeks out on parts. I asked them to put a rush on mine due to it being a daily driver, they said OK but you know how that goes. Also I am using a 5 layer aluminum gasket, and Mr. Gasket locking header bolts. As far as the chip goes I'm using Harris performance www.tbichips.com If you look through his website he's got a lot of great information on how to spruce up you ride.

92RS-HeritageEd

iTrader: (2)

I'm still on the fence with the headers, and the chip I had to bail on checking that out this morning because I didn't know how the ECM is mounted under the dash. I'll have to take a closer look at that tomorrow taking pics along the way.

mikeyt

You can use a Haynes manual or youtube video for removal of the computer. I'm also using www.tbichips.com

mikeyt

Have you done anything with it yet?

J-money

The Ultimate TBI part where you modify the throttle body seemed intimating to me at first aswell but its not so bad. That was my first time using a dremel but the mod is free if you have one already.

Schurkey

Any dyno numbers to show that spending all day "smoothing" the TBI makes any horsepower difference at all?

92RS-HeritageEd

iTrader: (2)

Based on my understanding of the The Ultimate TBI series under the How-To's, the TBI dremel MOD was only to increase air flow into the engine, and I could be SOOOOOOO wrong. I know more air equals more power...as to how the miniscule amount of additional power gained actually equates into measurable pony's...I know that I don't know. I'd like to know though, it may make me by a dremel and give it a go.

J-money

My car felt alittle better when I did mine but I also rebuilt the throttle body aswell so I cant really tell how much of it would have came from the mod. Its not to hard just time consuming.

Schurkey

Yeah, that's kinda what I thought. Lotsa grinding, lots of wasted effort.

A Dremel would be the second-to-last tool I'd use to perform the work. The last tool I'd grab would be a hand-file. Welcome to the world of die grinders and rotary files.

92RS-HeritageEd

iTrader: (2)

I have no experience with either tool you referenced Schurkey, and J-money I was thinking of doing either a replacement (Upgraded) TB, or a deep cleaning of the stock one. I will say over the last couple of weeks I've switched fuel grades from reg to mid and it seems to run better and get better MPG (Nothing Measurable), just seems to burn gas slower...

Schurkey

First Guess: There's not a thing wrong with your TBI unit that a bottle of Techron from the local NAPA or CarQuest or O'Reillys, and buying Top Tier fuel when available wouldn't take care of. Grinding on the air entry it is a TOTAL waste of your time. Rebuilding it ("deep cleaning") is similarly a waste of enthusiasm.

It might be worth your time to pop the TB off the manifold to verify that the base gasket is in good condition--in other words, replace the gasket.

When it was me, I tested fuel pressure, wasn't quite satisfied. Stretched the spring in the OEM regulator a bit. I ended-up with 11.5 psi; and under full-throttle, high RPM conditions (maximum fuel demand) my O2 and fuel trim readings are still good.

J-money

Have you done anything to it other than open element?

92RS-HeritageEd

iTrader: (2)

No Sir J-money, completely stock. That's why I was leaning on the members here and their mega-tons of experience with these cars and more importantly the freggin L03. I know it may not be the best in the V8 family but it's what came in my current ThirdGen and I need to make the best of it...as close to free as possible of course.

J-money

If it hasnt been tuned up in awhile that would be a good place to start. I think I went with MSD and Taylor stuff because they came in red lol. Stock exhaust on these cars isnt too great either. It would probably be simpler to pick out headers y pipe cat and cat-back to muffler all at once. Or you could just start with a cat back system.

Schurkey

From a performance-to-dollar standpoint, the FIRST thing to do is to assure that all the horses that GM installed are still there.

In approximate, sorta-kinda order of importance:

1. Assure that the engine is running properly--all "tune-up" items are in good condition.

• Distributor in good condition
  • Pickup coil
  • Module
  • Distributor wiring harness including capacitor if used
  • Distributor cap and rotor
• ECM controls timing as intended, includes setting the initial timing appropriately.
• Ignition coil in usable condition. No internal damage to insulation
• Spark plugs reasonably fresh and not fouled with oil or gasoline
• Spark plug (and coil) wires reasonably fresh, no "corona" light-show, no excess resistance, no burnt ends
• Fuel pressure adequate
• Fuel filter not restrictive
• Air filter adequate
• OEM air cleaner housing with the hot-air intake vacuum hose disabled in warm weather, and the cold-air ducting in place.
• Cranking compression test--cylinder pressure reasonably equal and adequate
• Cylinder balance test reasonably even individually, and upper/lower planes of the intake manifold equal.
• EGR functions properly (reduces likelyhood of detonation and engine damage)
• PCV functions properly (extends oil and bearing life)
• Fuel tank venting works OK, including charcoal canister and canister filter. Cuts emissions, doesn't hurt horsepower, assures no over- or under-pressure of the tank which can affect fuel pressure.
• AIR system (if used) functioning properly. Prevents backfire on deceleration, catalyst melt-down
• Knock sensor NOT causing excess timing retard (sensor not falsely triggering due to excess engine mechanical noise)

2. Starting/charging power team working acceptably

• Alternator charges at ~14.2 V (somewhere between 13.5 and 15.5, I prefer somewhere between those two extremes.)
• Battery holds a charge
• No excess voltage drop from alternator to battery
• No excess voltage drop from battery to starter
• No excess voltage drop from battery to passenger compartment
• No excess voltage drop from battery to fuel pump
• No excess voltage drop from battery to ignition
• No excess current draw when starter is cranking
• Starter cranks acceptably fast
• ECM is properly grounded

3. No active or pending codes stored in computer.
4. Replace pellet-style catalyst(s) with monolithic "high flow" aftermarket catalyst(s) It's extremely unlikely that the original catalyst is still healthy; and the aftermarket cats flow more.
5. Exhaust system has no damage.
6. Exhaust pipes replaced with mandrel-bent tubing, preferably of somewhat larger diameter.
7. Cooling system maintains reasonable engine temperature, no coolant loss, especially:

• Coolant loss into combustion chamber
• Coolant loss into oil
• No bloated (ready-to-burst) coolant hoses

8. Acceptably low engine oil loss, especially

• Oil loss into the combustion chamber Oil in chamber promotes detonation and plug fouling
• Oil loss into the exhaust port

AFTER you have CONFIRMED that all eight cylinders are making the power they're supposed to, you could move along to chassis verification. Your engine is making power, but you need to assure it's not being unreasonably robbed by the chassis.

1. Brakes don't drag, causing excess brake wear, poor performance, poor economy

• Low-drag front calipers (if used) are working properly
• Low drag master cylinder (if used) working properly (doesn't have low brake pedal)

2. Wheel alignment OK. Excess toe can cut fuel economy and harm performance (makes the steering squirrely, too.) Includes "thrust" alignment at rear
3. Wheel bearings have usable grease, adjusted properly.
4. Steering/suspension linkage and bushings in good condition
5. Ride height acceptable, prevents U-joint binding
6. Tires inflated
7. Torque converter OK. Free-wheeling stator one-way clutch kills low-speed acceleration. Seized stator one-way clutch kills high-speed power.
8. Transmission actually has all the gears it's supposed to

AFTER you have CONFIRMED that the chassis isn't working against you, you can see results from "hot rod" engine performance items:

1. Headers and Y-pipe
2. Higher ratio rocker arms
3. Replacement cylinder heads
4. Replacement camshaft + extensive FI tuning
5. Yeah
6. Yeah
7. Yeah
8. BLOWER or NOS, baby
9. 5.7L, "383", "400", Big Block, or LS transplant and significant FI mods

J-money

https://www.summitracing.com/parts/sum-680022

https://www.summitracing.com/parts/w...t/model/camaro

J-money

Those were the most affordable ones Ive seen for our cars so far.

92RS-HeritageEd

iTrader: (2)

Well J-Money, I can't speak to the tune of the car as I haven't done a bare bones or full tune up since purchasing it about 2 months back. Schurkey provided a detailed list, better than my Haynes manual which was rather vague for a newbie so now I have a better starting point. Headers i'm on the fence about (project difficulty). However I did throw a Walker SoundFx (Budget Friendly) Cat back system on there. It just doesn't give it the growl I'm looking for so I'm now reconsidering it. Excuse the expression but i'm a true automotive newbie with no mentor...How TF am I supposed to check all those components lol, i'll check for threads as i come to various parts in the list.

Schurkey

The best way to have a "nice sounding" car is to not have a wimpy engine ahead of a fancy exhaust pipe 'n' muffler.

Leave the new exhaust parts alone. You've already spent that money. Do you have a pellet-style, or monolithic-style catalyst, and is it any good? Were there any "beads" in the old muffler? If it's a pellet-style cat, swap it for an aftermarket monolith once the tune-up and chassis-check is done.

I'm not sure I ever knew when GM switched from pellets to monolith. My '03 Trailblazer is monolithic; I'm not sure about my '93 Lumina. I think the 88 K1500 had pellets before I converted it to monolithic, the '77 Nova has pellets (for now).

1. Find a local mentor. Take out an ad on Craigslist. Join a local car club. Enroll in an evening or weekend Community College auto mechanics course.
2. Welcome to "Problem-Based Learning". You'll learn as you solve problems. This is difficult, but effective. You'll certainly retain what you learn--but--you'll learn a lot of stuff "the hard way".
3. On-line mentors are better than nothing. Get a REAL digital camera, learn to take in-focus photos of what you need help with. Then crop and re-size them as needed, and post the photos along with WELL-THOUGHT-OUT text. Do not post enormous photos that need shitloads of scrolling, and don't post fuzzy, low-resolution cell phone pictures of any size.

J-money

That is good advice.

86firebird350

92RS-HeritageEd, I was once in your position of wanting to mod an L03 engine on a severely limited budget and not a lot of know-how. It is tough. The good news (if you want to look at it that way) is that these cars were so poorly designed from a performance aspect from the factory and most are so old and worn out by now that LITERALLY ANYTHING you do that is supposed to increase performance will yield a noticeable difference (however slight), even some maintenance items (like bushing replacement).

For someone like yourself who is just starting out with modding cars, my best advice is to read, read, read these forums. There is lots of good info to be found. That said, if you haven't checked it out already have a look at the technical articles on the site, specifically the ones pertaining to TBI. I have linked the page at the bottom of this post.

On cars these old, all mods should only be done after a thorough tune-up. Schurkey has already detailed this a few posts up. Once that is done, you can move on to the good stuff.

As far as actual mods go, the cheapest, easiest, and best "bang for the buck" mods from my experience were: an open element, lower temperature thermostat (I would recommend not going lower than 180*), adjusting timing, and underdrive pullies. These range in price from free to about $200 but definitely yielded improvement in throttle response, acceleration, and usable rpm range.

Mods I have not had any personal experience with but are relatively cheap and will increase performance would be: Ultimate TBI mods part 2, swapping to an aluminum driveshaft, and swapping rear ends. Personally, I did not do the Ultimate TBI mods to the throttle body itself because I chose to buy a Holley TBI unit, but with that said, LOTS of people have done it with good results. Afterall, it's a sticky at the top of this page for a reason.

The reason for swapping rear ends is to kill 2 birds with 1 stone (i.e. to go from drum brakes to disc and to get a higher rear gear ratio). I went the more expensive route of buying gears and adding a limited slip instead of swapping rears. Swapping gears was BY FAR the best mod I ever did in terms of biggest seat of the pants difference. It also dropped my 1/4 mile time by about 1/2 a second.

Another thing you could do to make the car quicker is to remove unnecessary weight. A good rule of thumb is every 100lbs removed = 0.1 second time reduction in the 1/4. Places where weight can be removed is with the spare tire and tools, A/C (if non-functional and you don't intend to use it), smog removal, aluminum water pump, intake, or heads, fiberglass hood, lexan vs glass t-tops, etc.

There are of course other mods that I have not mentioned here that will yield significant results, but they're more expensive and I would not classify them as budget friendly.

https://www.thirdgen.org/technical-articles/

92RS-HeritageEd

iTrader: (2)

Funny Schurkey mentioned problem based learning... I happened to be out dropping off some food to a friend and I began hearing this clanking sound (gears beginning to grind) coming from my Rear End, I head over to the garage this morning and my Differential Oil was low. No seals were leaking, no visible dripping, nothing. How does something like this get low, and how do I prevent it if there's no dipstick to check the levels. I was told the P/O did alot of burnouts...is that the root cause?

Schurkey

HOW low?

First Guess: You hear "gears beginning to grind", you might as well start looking for another axle, or expect expensive repairs.

Realistically, there are two ways for rear-axle gear oil to get "low". A small percentage of the liquid lube will vaporize over time. This is no different from engine oil, where the most-volatile fraction of chemicals will "escape" given some heat and time. This is a VERY, VERY SMALL amount. The other way is...leaks. Either you just haven't found 'em yet, or the last person to work on the axle didn't fill the fluid properly to begin with. Pinion seal, and axle seal leaks are the most common. Axle seals leak into the brake area, so the fluid collects brake dust. Takes a big leak to cause drips. A crack in the housing, or a bad gasket/silicone seal where the cover bolts to the center housing are about the only other places fluid can escape.

If the axle housing goes under water--deep enough for water to invade the housing via the vent--the grease will float out the vent when enough water gets inside. Axle gets hot from lack of lube, the water boils out leaving a low grease level (and a lot of icky debris inside.) As this is pretty-much guaranteed to ruin the gears 'n' bearings, you'd know if this happened.

You check the fluid level by unscrewing the fill plug, and sticking your finger in there. Fluid level should be very near the bottom of the fill plug threads.

No. Not especially good for the axle, it's hard on the spider gears and the shafts they turn on particularly when only one wheel is spinning. I don't suspect it as a cause for fluid loss.

chazman

iTrader: (4)

Replace you 048 ignition control module with 369 unit. It'll make a huge difference. Look it up...

92RS-HeritageEd

iTrader: (2)

Schurkey, no wonder you're a supreme member! When I left my mechanics this morning they came to the conclusion the gears, etc were in good shape, and that the P/O didn't fill to the proper fill level, but we did also discuss the possibility of a Rear End swap with higher gear ratios, and disc breaks...but that seemed expensive so I bailed.
Chazman, I'll look into my current ignition control module and swapping it with a 369 unit...Can you bullet point any benefits you've experienced?

chazman

iTrader: (4)

I drove two cars last year. One was an L03, 700R4, 2.73 and one was an L03, T5, 3.08.

The first literally felt like a tractor, good torque, but all done by 3500 RPM. The other felt great. Eager to rev, chirps between shifts, strong until 5000 RPM.

The two cars could not have driven more differently. Now I get the gear and trans advantage, but there was more to it. I speculate it was the ICM.

I got this from another site:

J-money

I remember seeing this last year but couldnt remember where. I just recently changed my module and forgot all about this and just went with a stock BWD brand version. Always did wonder how much truth there was to it.

Schurkey

Why is the ignition module, and not the computer controlling the timing? Does not make sense. Does not pass the giggle test.

Does GM list different part numbers for these two modules in the carline/truckline parts books?

chazman

iTrader: (4)

Here you go. For when you stop giggling.


http://www.chevytalk.org/fusionbb/sh...hp?tid/205486/
https://www.thirdgen.org/forums/diy-...ncy-table.html
https://www.thirdgen.org/forums/tbi/...i-l03-rev.html

DynoDave43

iTrader: (11)

RBob and Fast355? (I think that's who that is posting on the truck forum 1983G20Van). Two people I would trust for sure.

Schurkey

Woof. Just f'n WOOF!

I don't pretend to understand it all. Still studying--and researching.
1. I'll be checking the module in my '88 K1500.
2. How did I spend so much time in the Chevy world without knowing about this already?
3. I wonder if they've ever tested the "Marine" module--the one that is intended to be used WITHOUT a computer. There is a "centrifugal advance" built-into the module that advances timing based on RPM. I've known about that for a decade; in fact I own the small-cap HEI "Delco Voyager Marine Ignition" the module is intended for. It's a Coast-Guard approved distributor, coil, and harness kit intended to upgrade old "points-style" inboard boat engines.
4. One--of many--things that don't make sense to me is the idea of "latency" causing spark advance. I would have guessed that latency can only retard timing, not advance it. [Enterprise Computer Voice] Working! [/Enterprise Computer Voice]

DynoDave43

iTrader: (11)

Schurkey

I've checked NAPA website, along with AC-Delco web site.

I have no idea how you'd go about selecting one module over the other. Both sites list the same module for my '88 K1500 as the 94 G20 Van, and '92 Camaro Z-28 5.7L.

Delco number comes up as D1943A
NAPA number is TP25 (premium) or TP25SB (Discount line)

Suspicion: The "048" module is an older, discontinued version. The "369" is the updated replacement with better performance.

This is not unprecedented. The first year or two of HEI production used a 4-pin module that wouldn't perform past 5K; the updated version will go well beyond that.

It may be that GM did not intend the 048 module to be a performance-killer. Maybe they just screwed-up, and then fixed the mistake with the later unit.

Still need more research; and will be popping the cap off my K1500 tomorrow.

DynoDave43

iTrader: (11)

I've wondered about this one.

http://performancedistributors.com/p...d-distributor/

Schurkey

Sort-Of progress update:
Owing to lack of time, I did not build charts of RPM vs. Spark advance for the 048 module I found under the cap of my K1500, and the 369 module I found in my parts-stash. I did, however, swap modules so the 369 is now gainfully employed in the truck, while the 048 is currently gathering dust on the shelf.

I installed an MSD 6T on this vehicle years ago. The 6T is triggered with the distributor module in the circuit; whatever timing advance the module/computer provides is what is "fed to" the 6T. However, I discovered that the last time I dicked with the ignition system (I installed cap, rotor, plug wires, etc. about a year ago--maybe more--and then took photos of the oscilloscope pattern with and without the MSD in the circuit) I forgot to re-connect the 6T. The truck now has the 369 module and the 6T active. I will drive it and see if there's a noticeable power or fuel economy improvement.

Base timing has not moved with the replacement module and the MSD spark-box. Still at 0 degrees advance at idle with the brown/white wire disconnected. This is spec, and I set this back when Fido was a pup.

I did verify that with the wire reconnected, I have spark advance at idle, and the spark advance changes with RPM. This is easily read-out on the "magnetic timing light", a Snap-On MT-1480 Lumy/Mag II.








Research Update:
"048" and "369" are the last three digits of the GM part number.

As alluded-to in my previous post, NAPA and other ignition parts companies consider the 048 and the 369 modules to be interchangeable. Both of them--ALONG WITH OTHER MODULE PART NUMBERS--are replaced by a single basic part number.

I do not understand how modules that affect the spark advance curves differently can be interchangeable, when spark advance is going to affect emissions control. You'd think the EPA would **** on GMs Wheaties for changing the spark advance without doing emissions testing/approvals. Additionally, I wonder how the change in spark advance affects knock-sensor tuning.

NAPA does show five basic part numbers for "8-pin" small-cap HEI modules that seem externally identical. One of them is the "Marine" module. The other four, I have no clue what makes them different.

List of NAPA vs. GM 8-pin module interchangeability, as published in June 2004 Illustrated Parts Guide:

NAPA TP18 = GM 10482831, 16129419, 16139409 (Chevy, GMC truck '88-98) (but not used in MY '88 K1500, apparently.)

NAPA TP22 = GM 1987465, 1987466, 10457765, 10482834, 12350347, 12350348, 12350350, 12350352, 16140039, 3-3029 (Buick, Cadillac, Chevrolet, Chevy/GMC Truck, Olds, Passport, Pontiac) 1985--1993 (select models)

NAPA TP24 = GM 1989747, 10482828, 10482829, 10496269, 16139379, 16139389, 3-3101
(Asuna, Buick, Chevy, Chevy/GMC Truck, Olds, Passport, Pontiac) '85--94 (select models)

NAPA TP25 = GM 10469931, 10482827, 10496047, 10496048, 10496541, 12350348, 12350350, 12350352, 16139369, 16139879, 133-4407, 8-10496-541-0, 3-3102 (Asuna, Buick, Cadillac, Chevy, Chevy/GMC Truck, Geo, Isuzu, Olds, Passport, Pontiac) 1986--1997 (select models)

Note that the 12350350, and the 12350352 can be replaced with either the TP22 or the TP25. Go figure.

What the fukk is an "Asuna"???

[Forest Gump Voice]An' that's all I know about THAT.[/Forest Gump Voice]

Schurkey

Wild-azz Guess: It's a NAPA TP25SB (discount line) equivalent with a sticker on it, packaged into a fancy box; and with 50% added to the cost.

Schurkey

Oh, for fukk sakes.

Went back through https://www.thirdgen.org/forums/diy-...ncy-table.html

Am I reading this right?

Every time RBob compares the two modules (048 and 369), he's switching the latency tables that alter the timing information. The 048 is tested with Table 1, the 369 is tested with Table 2. The change in timing is due to the latency tables, not the modules.



I have PM'd RBob asking questions. I'm hoping he'll post here directly.

If this is right--and I believe it is, although I'm waiting for confirmation by RBob--I was correct to begin with. The COMPUTER controls the timing advance, not the ignition module; as a result there is no performance difference due to changing modules, the performance difference is due to changing THE LATENCY TABLE. The only time the module changes the timing is when there's a malfunction or the brown/white wire is disconnected. There is now no conflict with spark advance vs. EPA regulation or knock-sensor tuning, because all those part numbers listed as compatible with the NAPA TP25 really are equivalent--the 048 and 369 are functionally interchangeable as far as fitment and timing advance.

RBob

iTrader: (1)

This is the key post of the latency thread:

https://www.thirdgen.org/forums/diy-...ml#post3775917

And a statement from that post: "With this change running the RPM from 800 through 3200 had each module with the appropriate table holding a steady SA. Switch the table and the advance moved around as the RPM changed. "

The 048 and 369 ICMs do have different latency's. Match the latency table with the module and the SA matches until above 3200 RPM or so.

Swap tables and the SA moves all over the place.

RBob.

RBob

iTrader: (1)

To be honest I wouldn't use it. I would get an AC Delco 369 ICM.

One thing that bothers me about the Dyna module is that they claim it controls the dwell. With stock ICMs the ECM controls the dwell, and does so quite well. I've also seen aftermarket ICMs current limit the coil at a lower current then the GM ICMs.

RBob.