Clubuser

Car: 87TII. Engine rebuilt about 15K ago. Has a mild street port. Produces ~105 PSI when cold (every sweep). Pulls ~12 inHg @ ~900 RPM. Engine ran perfect prior to disassembly for installation of the Rtek7 v1.8 along w/an XO2 FMIC. This project was recently completed.

The engine hesitates pretty severely under part throttle, light load conditions. However, the engine's idle (~900), no load revving, and response above 2700-2800 RPM under some load/boost is EXCELLENT.

This past Sunday (Feb 6, 2010), I discovered by disconnecting the vacuum line (or the connector) to the MAP sensor made the problem DISAPEAR!!. A/F ratio (per my narrowband O2 LED meter) went right to the rich end and stayed there (and that's w/a running smog air pump). Makes sense that by disconnecting the vacuum line the ECU sees more voltage hence more fuel. It ran perfect (light load of course) with the vacuum line off. While experiencing said problems, A/F ratio is quite higher than stoich.

The MAP sensor works perfectly. But to eliminate doubt, I swapped it w/a backup MAP to no avail.
Both sensor's while idling produced ~1.31V @ ~12.5 inHg and ~1.20V @ ~14 inHg and respond smoothly to changes in vacuum.

TPS is adjusted per shop manual using the 2 light technique @ ~800 RPM. Fuel pressure is perfect.

Sure sounds like the ECU is having issues w/ addressing sufficient fuel under the said conditions!!

I've hit a brick wall here. Without saying, your suggestion much appreciated.

I encountered a few bumps getting to this point. As a result, all critical sensors have been doubled checked and all found to be in perfect working order. Thanks much to ARGHX and Rtek7 for their help during the bumpy ride.

Clubuser

These are the injectors I'm running:

http://cgi.ebay.com/ebaymotors/4-Maz...Q5fAccessories

Nick_d_TII

iTrader: (6)

OH NO! TLF performance!? Have those injectors flow tested(even if they came with a sheet). I bought a set of 800cc's and one flowed about as much as a 550 and the other about 700 or some ****.

TLF performance = Venom = Junk

Sorry. Can't believe he's in business still.

http://www.google.com/#hl=en&source=...4af607061c90a3

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/anyone-heard-about-these-venom-1600cc-side-feed-injectors-402841/

lastphaseofthis

iTrader: (8)

can You snap a pic of your engine bay, specically how your AFM is setup.

Clubuser

Here' link to some pictures:
https://www.rx7club.com/showpost.php...6&postcount=15

One of them shows the AFM. You can focus in to get a better view. Currently it's horizontal. Between AFM and turbo is a 3" I.D. wire reiforced flex hose. I've run this setup (as in the picture) for a while with perfect results.

Clubuser

Now that sucks. I can tell you this, I have the idle mixture resistor almost maxed out. Flow testing them and coming back different than advertised should give me grounds for a refund. However, as I've stated the problem is not under all conditions.

lastphaseofthis

iTrader: (8)

from running the perfect to now, was the injectors the only thing changed? running with the flapper door opening tewards the ground can cause richness, as gravity pulls on the flapper. having it vise versa can cause lean conditions. just something to think about. i've used that method to lean out and N/a i had a while back. too bad a never had a wineband to prove it.

Clubuser

1) Yes.
2) I agree. I think it's a given. That's why I believe those running into lean condition w/ an Rtek7 2.1 could squeeze out a few extra HP by orienting the AFM so gravity works against the flapper. The extra air required to fully "lift" the flapper can then be addressed w/ extra fuel.

Gian

iTrader: (3)

When doing Diagnosis on anything. Try to keep it simple (as possable).

As everyone else has pointed out. Injectors seems to be the only thing you have changed.
When ever you start changing things. Making sure everything works together is a must. But it is hard to do by guessing. Put it on a dyno. See what is really happening.

I know dyno time cost$$$. But the time you'll save it worth it.

Sounds like its going lean. But again, thats just a guess.

gxl90rx7

iTrader: (1)

a lot of other poeple have had the same problem including me, running a new o2 wire helped me, but never got rid of the problem. i still think its a bug in the rtek code. i always had the problem with 2.0, but when i switched to haltech the problem disappeared.. didnt change a thing besides the ecu

https://www.rx7club.com/rtek-forum-168/fixed-my-hesitation-100%25-time-681555/

Clubuser

Thx much for the feed back. Makes me feel better I'm not the only one having experienced this nightmare. I find it hard to accept it might be the injectors. Why does it run fine otherwise? Anyways. still have to remove the injectors to flow test but I think it will be money down the drain.

I was running a Superchip prior for several years and ran flawless. So I don't buy that my street port can cause such severe conditions.

lastphaseofthis

iTrader: (8)

I didn't think of that, can you look at the ecu and see if it only does it when in closed loop?

Nick_d_TII

iTrader: (6)

http://www.celicasupra.com/forums/sh...-Injectors-BAD!

http://www.supraforums.com/forum/sho...d.php?t=393612

http://forums.hybridz.org/index.php/...injector-scam/

http://www.gtr.co.uk/forum/91299-ven...ctor-scam.html

http://forum.clubna-t.com/showthread.php?p=75236

http://www.skylinesaustralia.com/for...nom-injectors/

Some comments about Venom Injectors from the sites listed above.

"When I got my first set I flowed them and **** was WACK. I got another set from him and guess what, WACK **** x2...lol Injectors were leaky and flowed like crap. That flow sheet, give me a ****** break, that **** was typed out using some BS program. I had a good buddy flow 12 injectors for me or 16 and NO sets were equal. I told Venom this isnt good and basically said im not risking my reputation on the board here or screwing anyone's motor up. After selling like 3 sets I was like forget this after I saw how all the ones I had were. Tom will tell you a lot of BS ****. How many Delphi or Siemen injectors do you hear of going bad and getting "dirt" stuck in em. Give me a break. VENOM IS ****. STICKY THAT FOR EVERYONE."

"I bought injectors from tlfsupra89 which was one big mistake. Please do not make the same mistake and make sure no one does."

"hi all, the guys name is tom folder, i bought 6 x 1000cc from him , they where all *****, took 40 e,mails and threating to get someone near where he lived to go and have a QUITE word with him before he refunded 90% of my money.this guy is a real numbnut, for want of a better phrase.."

"Hi
Can also leave some bad feedback about these Injectors, bought 2 pairs from them. One pair 1000cc for RB26 and one pair 550cc to RB25 for a friend and guess what??? They are leaking a lot the guy with RB25 had the ignition on for a time and suddenly fuel was coming out of the exhaust

DONT BY THIS CRAP"

Your primaries are probably ok, but your secondaries are probably junk. But hey if you want to 'trust' them go ahead but don't say you haven't been warned.

I got 2 Venom 800cc's in a box, you want them, $20 bux + shipping, but like I said, they flow like 550 and 700 or some crap.

Clubuser

Like I said they will be tested. And I do appreciate the warning. Likely I wouldn't be doing it if you hadn't passed on your experience.

Clubuser

Just got back from WitchHunter the injector's (mentioned in post #2 above) flow test . #s are 696, 705, 726, 750. What a coincidence the average is 720.

I also noticed I didn't bolt down tight the ECU's ground wires that bolt down to the block under the TB's area. Actually, they were quite loose.

Not knowing how I had the injectors placed and loose ground wires were most likely the cause of all my issues.

The engine is still apart waiting for EBay to contact me regarding my claim for a refund on the injectors. Worst case I'll pair them up (96+750 and 705+726). Engine will just be a little lean on the primaries.

Clubuser

The cause was the loose ECU gound mentioned in my post above.

Finally got everything reassembled this weekend. Had been waiting for the adjustable FPR to arrive. With the fuel pressure set @ around 8% greater than stock (to compensate ffo the ~700 cc primary injectors) the engine fired right up and ran flawless.

misterstyx69

iTrader: (142)

If it was me,I would NOT be running the injectors with a "10 percent" Variation in flow.
I'd be looking at getting those injectors Replaced.No sense in blowing your engine.

Clubuser

Actually, it's more like 3% variation from 720cc on the primaries but little to no variation when all 4 injectors are active. It just happens the engine "likes" the higher fuel pressure.