Drakenheart

The standard thing 95 Suburban K1500/5.7 engine. Done all the standard tune up things, checked grounds and battery/alternator performance. Enging idles/runs OK when cold, the hotter it gets the more rough it runs. At high outside temps I hear detonation on acceleration miss occurs from idle to cruise RPM. Engine is not sluggish or down too much on power. Only mod is a 1" TBI spacer that's been on for 21/2 years. Here's the topper. Turn the air conditioning on and it smooths out considerably. Any Ideas?

73shark

Welcome to the forum. What's the TBI spacer do?

Drakenheart

The Spacer goes between the manifold and TBI Injector unit. It straightens the airflow and enhances performance. I found that the bottem end was most affected with increased torque. However, in max acceleration, the engine over-revs tach redline by 250 RPM.

73shark

I find it interesting that you have increased torque at the low end as spacers are usually sold as increasing hp at the upper end. Any dyno sheet to support this?

Drakenheart

Let's see, where to start. Checked the resistance of the ect sensor, about 400 Ohms off for the temp on the chart. Gonna replace that tomrrow. Injectors are stock. I have no dyno sheet to support my observation. Just feels stronger at initial acceleration. I cannot contest the high end either, the truck pulls better all the way. Like I said it will over-rev on the factory installe tach now. Next step when I get thr roughness to go away is a 1/4 in spacer that lifts the injectors themselves. Allegedly gives 10-15% more airflow for 10 bucks. May be the best performance bargain of the century.