Wont rev past 3krpm - tach jumps around

neoxaero · Dec 1, 2008

Car is being dyno tuned and it wont rev past 3k rpm... The tach in the dash bounces around like crazy..

Any ideas what it might be?

Car is running an AEM standalone, Spout is plugged in -- I'm thinking its distributor or TFI module.. ??

Thanks

Chythar · Dec 1, 2008

Does the engine actually change revs with the tach, or are the revs constant? If they're different, I'd suspect a bad ground on the block.

neoxaero · Dec 1, 2008

The engine just stops rev'ing any higher - its exactly like its hitting the rev limiter (which is set at 5800 - tried setting it to 8k but it made no difference.. btw)

I replaced the Ignition Control Module (on the passenger side of the car.. on the fender) with a new one from O'Reilly's and it ran like ****.. backfiring through the intake, wouldn't run..

Pulled the Spout and it ran fine (up to the 3500rpm mark)

vladasap · Dec 1, 2008

ill take a shot in the dark with saying its the dizzee

its just that the tach is controlled by the dizzee from my understanding and i know that if the dizzee is bad the tach tends to be all over the place

that will also explain the timing being cut at the rpm

neoxaero · Dec 1, 2008

Hmm..

Well - I said screw it and am chunking all the ford ignition ****

I'm going to an AEM Engine Position Module (EPM - AEM - Engine Position Module (EPM)* ) and run LS1 Coils on the car

Coil near plug would be different, and fun .. Should support quite a bit of HP too...

<3 GM products

toyman · Dec 1, 2008

neoxaero said:
Hmm..

Well - I said screw it and am chunking all the ford ignition ****

I'm going to an AEM Engine Position Module (EPM - AEM - Engine Position Module (EPM)* ) and run LS1 Coils on the car

Coil near plug would be different, and fun .. Should support quite a bit of HP too...

<3 GM products

I had the same problem. It's the dwell setting. When I get home later today I'll give you my setting to see if that solves your problem.

neoxaero · Dec 1, 2008

toyman said:
I had the same problem. It's the dwell setting. When I get home later today I'll give you my setting to see if that solves your problem.

Thanks man -- if the dwell setting would fix it... that would save me a whole lot of head ache

On a side note -- the stock ignition control module fell apart when i was taking it out -- had to have been the stock one..

toyman · Dec 1, 2008

neoxaero said:
Thanks man -- if the dwell setting would fix it... that would save me a whole lot of head ache

On a side note -- the stock ignition control module fell apart when i was taking it out -- had to have been the stock one..

Set the dwell to 20. Also in options check out the various ignition retard and cut values and the fuel cut values. Something there could be out of spec.

neoxaero · Dec 1, 2008

my dwell was set to 35 (looking at the map i have on my PC)

I'll call the tuner tomorrow to see if he changed this setting

Interestingly - the car was doing the same thing before the AEM -- only then it would free-rev w/o a problem .... Now its not free rev'ing either

However, 270ft/lbs @ 2600rpm btw

See what happens when the car actually runs

Wont rev past 3krpm - tach jumps around

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