Running rich (engine swap)

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Dec 4, 2006 | 12:45 PM

thnbluline50

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From: youngstown Ohio

Running rich (engine swap)

I'll try to make this short. 1990 vert, installed GMPP 383 with GMPP TPI Manifold. Will not idle unless I disconnect the MAP sensor (new). Blowing thick black smoke. I am no mechanic, all the work was done by the shop that installed the engine, they say it is running rich. Howell Engine development has burned 3 chips to fix the problem, bit to no avail.
15 area "engine heads" also looked at it in the past 2 years and cant fix it.
GMR Speed out of Hinkley, Ohio has told me that they can dyno-tune and they have the equipment to burn the chip to the right mixture.
I am a little hesistant to believe them as I have been dead-ended every time for 2 years. (I do have a pressure regulator, and new fuel pump)
Question is, should I let them try for $500.00 or save my money? Has any one done this with success? My last option is to pull the engine, put on a carb and put it in an old nova or Chevelle!

Dec 4, 2006 | 01:38 PM

byebyeL98

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From: Orange County NY

St. Jude Donor '10-'11-'12-'13

First, check to be sure it is mechanically / electrically sound (i.e. - no vacuum leaks, no injectors leaking, no valve seals leaking / all sensors working properly and reporting info to ECM). Have you (or a mechanic) checked all of this out? With that much black smoke, it sounds like it is more than just the chip.

Has Howell Engine Development had the car to run on a dyno while burning the chip, or is this mail / phone order?

We need a little more information about the situation to fully help out.

Dec 4, 2006 | 05:27 PM

C409

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From: Clearwater Florida

rich

What size injectors are you using ?

Dec 4, 2006 | 06:01 PM

RRT vette

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From: Louisiana

As stated, make sure everything is mechanically sound. A dynojet with a good operator should be able to find the problem. It's expensive, but it should tell them where to look.

Dec 4, 2006 | 11:23 PM

thnbluline50

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From: youngstown Ohio

well, I've been told by my mechanic (and the reciepts) that all of the items are new, sensors, injectors, and everything else you mentioned. Basically, EVERYTHING is new from the firewall up that has to do with the powertrain. I have also put in a brand new ECM as well as one of the mechanics said the chip was not working because the ECM was bad. That was a $100 dead-end.
I am NOT a totally un-mechanical guy as my first post may have led you to believe, but since I have started this 2 years ago, I am now doubting everything I knew about cars!

The injectors are 30LB and I am now wondering if I should put back the origionals?
I will take it to the dyno guy and hope for the best. If it does not work, I may take up restoring something easier, like mo-peds, or better yet 10speed bikes!!!

Thanks guys,

Dec 5, 2006 | 02:43 PM

C409

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From: Clearwater Florida

rich

The ECM will hold you in cold-start mode til it sees about 145 degrees
from the coolant temp sensor. Plus it is following the fuel maps for a 350 with 24# injectors . If you have increased fuel pressure as well that would also make for a smoky ride . The O2 sensor doesn't enter the equation til the temps are all up . Til then the ECM has no idea what's going thru the pipes . Try the original injectors @ 50 psi that should compensate for the additional cubes and get you in a more accurate fuel map .

Dec 5, 2006 | 03:25 PM

RRT vette

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From: Louisiana

Quote:

Originally Posted by Robert Hyclak

The ECM uses the CTS for start/warm up fuel adjustments. The CTS sends a resistance measurment to the ECM and as the engine temp increases the resistance decreases. You are still in open loop mode until the exhaust temp has reached ~600*F or about the ~145*f as mentioned (all depending on engine mods). This is when the O2 sensor starts sending voltage readings to the ECM. If the chip is stock, it is telling the ECM that the engine is still feeding off 22lb injectors, which with the 30lb you have now will allow more fuel in the cylinders than is needed.

thnbluline50, what is burnt into the chip you are running now? I assume you have headers...what about a heated O2 sensor?

Dec 6, 2006 | 02:07 AM

mseven

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From: The Motor City

Sounds like a number of possibilies, 02's can get contaminated on a fresh build from silicones, which can then cause a rich condition. The injectors may not be helping, but that all depends on were it is set at in the constants (inj.flow) from the tune those guys sent, and if they are sticking or leaking could have a similar result.
Is everything else hooked up, (est for the distributer comes to mind). With or w/out the map it is pouring black smoke? Any codes? Do you have a scanner? If there is a tuner near you, a scan would help understand a few things.